OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 6 2 4 Fig. 7. Surface roughness measuring device Surftest SJ-210 and an example of recorded data from the software of data exchange between the device and the computer tool. However, it should be noted that at this stage of the model validation, its results are valid in the case of tool wear on the main cutting surface not exceeding 0.1 mm. When this wear threshold is exceeded, the system starts to be dominated by its own evolutionary processes, mainly related to the plastic deformation of the material in the contact zone between the tool and the workpiece. Then the discrepancy between the experimental and modelled surface estimates of the workpiece surface roughness varies within 0.61–1.36 μm as wear progresses. Results and discussion The evaluation of the output characteristics of the cutting process based on the information on the tool vibration dynamics showed that there is an observed dependence between high amplitudes of frequency components in the vibration acceleration signal of the system natural motions and the workpiece contour error with respect to its roughness parameter (Fig. 8). a b Fig. 8. Spectral characteristic of the vibration acceleration signal for radial direction: a – Sp (0) = 0.15 mm/rev; b – S p (0) = 0.25 mm/rev Figure 8 shows that an increase in feed rate leads to an increase in the amplitudes of the part rotation frequency, the appearance of a large number of frequency components in the vibration acceleration spectrum in the region of the part rotation frequency and an increase in its amplitudes. This behavior can be characterized by a sharp increase in temperature in the cutting zone, material breakouts along the cutting tool path or an increase in the influence of kinematic disturbances on the dynamics of the cutting process. The levelling of such effects before the moment of intensification of tool wear allows the correct selection of cutting modes, which can be carried out for the considered problem with the help of the created digital simulation model. In this article it is proposed to choose the value of the dispersion of the auto-spectrum
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