OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 5 No. 4 2023 the form of a separate algorithm. The fi rst stage of design is the formation of an actual set of initial data (R, ds, α, γk, ω, Rt, φ, κ, η, L, lr, f, ν). The range for assigning the radius of the generatrix of the toroidal fl ank surface is consistent with the range for assigning the clearance angles and is compared with the established design database, which has a number of typical relationships between the geometric parameters of the drill. As a result, the algorithm determines the position of the section in which the value of the clearance angle α is set, or α is set manually. At the next stage, the profi le of the chip fl ute is formed based on the specifi ed values of the core diameter ds, back radius r and radial rake angle γk. Based on the profi le data of the spiral fl ute of a twist drill, a Boolean operation is generated that specifi es a 3D model of the workpiece with a spiral fl ute. An important stage in developing a drill model is the formation of the cutting surface. The geometric parameters that defi ne the Boolean operation are presented in the second operator of the algorithm. The tangent to the generatrix of the generating surface imposes a strict limitation, ensuring constant contact of the generatrix of the entire set of drill structures at a certain angle in terms of φ. The center-to-center distance between the axis of the toroidal fl ank surface and the axis of the drill is specifi ed by the parameter ν. The angle between the point of contact of the circle defi ning the toroidal generatrix and the point of intersection of the circle with the periphery η regulates the possibility of assigning a parametric and structurally related angle to the radius of the fl ank surface of the generatrix in terms of φ with a known radius of the toroidal surface Rt. The fi nal task in developing a parametric model of a twist drill with a toroidal fl ank surface is the formation of the fl ank surface. The fl ank surface is a toroidal surface obtained by rotating the profi le of the Boolean “subtraction” operation around an axis located at an angle ε to the drill axis and the position of the intersection point of these axes at a distance W from the drill axis. Moreover, the angle between the tangent to the fl ank surface and the tangent at a given point on the cutting edge of the drill with radius rp is the clearance angle α. A comprehensive CAD methodology allows producing both the most common and specialized designs of twist drills (fi g. 4). Based on the work of CAD and the resulting designs with a toroidal fl ank surface, a comprehensive study of the distribution of the rake angle along the cutting edge, deformations and stress state using the fi nite element method along the cutting edge for structures with diff erent types of sharpening Fig. 4. Technical drawing of a twist drill with toroidal fl ank surface
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