OBRABOTKAMETALLOV technology Vol. 25 No. 1 2023 The data obtained show that at the stage of the steady-state process, the value of the actual depth of micro-cutting varies according to the harmonic law and is not a constant value (Δtfi ≠0) in contrast to what is recommended to be taken in the classical calculation method [16]. The results of the calculations were verified by comparing the calculated and experimental data. Grinding was carried out on a Knuth RSM 500 CNC machine, characterized by increased vibration resistance to external influences. Initial data: the material of the workpiece is titanium alloy VT3, d = 150 mm, grinding head AW 60×25×13 63C F90 M 7 B A 35 m/s , circumferential speed of the wheel Vk = 35m/s, workpiece speed Vu = 0.25 m/s, radial feed Syi = 0.005 mm/r, number of grains per unit area ng = = 15.86·106 pcs/m2, corner radius the grain vertex r g = 7.31·10 -6 m). After processing the profilograms taken from the machined blanks, the relative error of the calculated data with the results of the experiment was calculated. The data are summarized in Table 2. Ta b l e 2 Relative error of calculations No. fi t 1 i rω - D i H Relative error exp 100 % H H H D δ = , % calculated experimental Pl. 1 14.91·10–-6 0 9.069·10–6 8.16·10–6 11.13 Pl. 2 25.53·10–6 5.884·10–6 13.74·10–6 12.53·10–6 9.6 Pl. 3 31.27·10–6 11.79·10–6 15.78·10–6 17.82·10–6 11.45 Pl. 4 33.89·10–6 15.49·10–6 16.56·10–6 18.88·10–6 12.29 Pl. 5 34.94·10–6 17.32·10–6 16.85·10–6 19.87·10–6 15.2 St. 1 35.33·10–6 18.09·10–6 16.95·10–6 19.9·10–6 14.82 St. 2 35.47·10–6 18.38·10–6 16.98·10–8 19.94·10–6 14.84 St. 3 35.52·10–6 18.49·10–6 16.99·10–6 19.97·10–6 14.92 N.1 20.55·10–6 18.52·10–6 11.68·10–6 12.73·10–6 8.25 N.2 13.66·10–6 8.867·10–6 8.451·10–6 9.3·10–6 9.13 N.3 9.78·10–6 5.211·10–6 6.437·10–6 5.73·10–6 12.34 3.343·10–6 A comparison of the calculated and experimental data indicates that the accepted mathematical models provide high accuracy of calculations (the relative error is less than 15 %) and make it possible to analytically determine the values of the output parameters of the internal grinding process, taking into account the influence of the relative vibration oscillations of the grinding wheel and the workpiece. Conclusions The interrelationships of processing modes with the current parameters of the contact zone when grinding precise holes are established, taking into account the mutual fluctuations of the tool and the workpiece, which allow determining the parameters of the system at the output to avoid cost losses, including reducing the number of defective products and time costs. Constructed non-stationary mathematical dependences allow determining cutting modes during the grinding cycle implementation, taking into account the magnitude of relative vibrations and the initial phase. It is established that instead of a steady process, harmonic oscillations are observed caused by deviations in the shape of the wheel, the intensity of tool wear and other factors, all of the above has a significant impact on the quality of the machined surface.
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