OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 5 No. 4 2023 Fig. 9. Graph of the dependence of the cutting wedge taper angle b on the ratio of the length of the main cutting edge at the inspection point measured from the initial position, to the total length of the main cutting edge For the diagram of equivalent stresses and displacements of drills with conical and toroidal sharpening of the rear surface, an FEM analysis is carried out using the above-mentioned method. The results of elastic displacements and equivalent stresses in the cutting wedge of drills with different sharpening shapes are shown in table 4. Analysis of the obtained results shows that the maximum stress for a drill with a minimum radius of the generative of the flank surface is the minimum of all the drill designs being considered here, which indicates a more rational distribution of width of uncut chip and geometric parameters along the cutting edge. The cutting wedge along the cutting edge has a cross-sectional area that is closest to constant, which allows us to identify the best strength characteristics of a drill with a toroidal sharpening with a minimum radius of the generatrix Rt min, which forms the rear surface. The stresses at points of the cutting edge equidistant from each other are considered, and the angular values of the position of these points from the drill axis are measured according to the design method for drills with a toroidal flank surface. The results obtained are Ta b l e 4 Results of an epure of the maximum equivalent stresses and displacements in the cutting wedge for drills with different parameters of the flank surface Type of FEM analysis Conical flank surface Toroidal flank surface (2.5 R) Toroidal flank surface (1.25 R) Toroidal flank surface (Rt min) Movements max = 0.049 mm max = 0.052 mm max = 0.050 mm max = 0.045 mm Equivalent stresses max = 1465.926 MPa max = 1412.569 MPa max = 991.473 MPa max = 874.013 MPa
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