OBRABOTKAMETALLOV Vol. 26 No. 1 2024 TECHNOLOGY In addition, to simulate the temperature calculation, it is necessary to take into account the geometry of the cutting tool (front angle γ, back angle α, cutting edge inclination λ, peripheral angle ϕ). It is equally important to determine the schematization of the milling process (terminal, cylindrical, end), and also take into account such parameters as the cutting depth e, the ratio of the milling width to the diameter of the cutter and the number of teeth working simultaneously. For example, a changing in the front angle γ leads to a change in the inclination of the conditional shear plane, a change in the ratio of the contact length to the thickness of the cut layer, a change in the deformation, which ultimately aff ects the change in cutting powers [24]. Changing the inclination angle of the cutting edge (angle of elevation of the screw groove) and the angle in plan (peripheral angle) leads to a change in the thickness and width of the cut layer, which also aff ects the cutting powers: ϕ λ ; sin cos t b = ⋅ (12) θ λ sin cos , z m a S = ⋅ (13) where a and b are the thickness and width of the cut layer, accordingly; t is the milling depth; Sz is the feed to the tooth; θm is the angle of contact of the milling tooth with the processed material. To improve the accuracy of calculations, such characteristics as the Peclet – Pe criterion, characterizing the speed of the heat source movement and the Peclet – KPe coeffi cient, taking into account heat exchange with the environment, were added into the model [16, 17, 27]. Changes in the properties of the processed material depending on changes in the cutting temperature were also taken into account (fi gure 3–4). Ta b l e 2 Mechanical and physical properties of aluminum alloys required for temperature calculations Material grade Ultimate strength σu, (MPa) Ultimate elongation δ, (%) Heat conductivity factor λ, (W/m·K) Volumetric specifi c heat СV, (MJ/m3·K) Temperature diff usivity coeffi cient ω, (m2/s) Density ρ, (kg/m3) D16T* 460 16 120 2.56 4.95ˑ10-5 2,800 AMg6M* 320 24 122 2.43 5.44ˑ10-5 2,640 2024–T3* 435 15 121 2.43 5.68ˑ10-5 2,780 * Rolled sheets Fig. 3. Changes in the heat conductivity coeffi cient of the studied group of materials depending on temperature changes
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