OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 7 1 5 The simulation results for the coordinate representing the deformation motions of the cutting tool tip in the radial direction, with the wear of the cutting tool along the back face of 0.29 mm, are shown in the figure below. As can be seen from the figure, the amplitude of the deformation motions increases significantly, and for this cutting case, the calculated Ra value reaches 2.2 μm, which is substantially higher than the previous calculated values. This jump is due to the transition of the wear curve from the stabilization region to the region of critical wear. Let’s consider another cutting scenario, characterized by the wear of the cutting tool along the back face of 0.344 mm. The simulation results for the y-coordinate for this case are shown in Fig. 23. A comparison of Figs. 22 and 23 shows an even greater increase in the vibration amplitude of the cutting tool, including in the radial direction. The calculated surface quality parameter for this case reached a value of 4.17 μm, which is a very large value for the case of metal turning and can only be considered as a roughing or pre-finishing option. In total, we conducted nine experiments to construct the curve of surface quality variation during cutting. For clarity, let’s consider both the experimental evaluation and the model evaluation of surface quality variation. To do this, let’s examine the variation of Ra for the case of experimental data, based on the interpretation of this parameter using the data presented in Figs. 8 and 19. The interpretation of the data from Table 4, presented as a combined graph of two characteristics, is shown in the figure below. As seen in Fig. 25, in this case of comparing simulation results with experimentally obtained results, both characteristics exhibit a very high degree of similarity. There is a slight discrepancy in the region of average values of the value characterizing the wear of the cutting tool along the back face, but overall, the characteristics are almost identical. Fig. 23. Example of calculating the quality index at h = 0.314 mm Ta b l e 4 Values of the quality indicator Ra (experimental and modeled) Wear (mm) 0.11 0.16 0.22 0.23 0.26 0.29 0.314 0.344 0.402 Ra (μm) (modeled) 1.26 1.22 0.96 0.84 0.98 2.2 2.9 4.17 41 Ra (μm) (experimental) 0.516 0.52 0.53 0.532 0.602 0.97 1.45 1.6 39
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