OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 7 5 Fig. 7. Examples of spectral changes of a standard pulse sequence a b c d The calculations indicate that increasing the uncertainty in the emission signal over time leads not only to broadening of the emission signal’s spectral line but also to a decrease in the intervals between pulses due to regular spatial shifts in the signals. Therefore, as wear increases, the emission signal spectrum becomes blurred and shifts toward the high-frequency region. It is important to note that each individual pulse has risen and fall stages that depend primarily not on time but on the path of relative movements; thus, increasing the cutting speed reduces the parameters Ti (N,k) and ΔT i (N,k). As a result, the spectrum becomes dependent on the cutting speed. If we analyze the frequency range ∆ω ∈ ω ω 0 0,1 0,2 ( , ), we observe that the main changes in the frequency spectra with increasing wear correspond to the features described above. Moreover, the upper frequency ω0,2 in this range is determined by the rule: − ω = 1 0 0,2 P h V where h0 is the height of the contact between the flank face and the workpiece at the initial stage of wear w = 0; it depends on the elastic recovery of the material. The lower frequency is − + ω = 1 0 0,1 P h w V . This range must be adjusted experimentally. Here is an example of changes in the spectra obtained from the sequences measured by the cutter shown in Fig. 6, b when turning 0.1 C-Mn-2 Ni-Mo-V steel at the following cutting conditions: feed rate Sp = 0.1 mm, depth of cut tp = 1.5 mm, and cutting speed V3 = 1.2 m/s (Fig. 8).
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