INITIAL TOOL SURFACE OF DISC-TYPE MILLING CUTTERS BASED ON A SINGLE-SHEET HYPERBOLOID FOR THE MANUFACTURING OF INVOLUTE GEARS

This study focuses on the design of assembled disc-type gear milling cutters based on straight-edged carbide inserts, which form a gear tooth profile approximated to an involute. By means of a specific insert positioning, these deviations are minimized, resulting in calculated profile errors comparable to those of profile-shape cutters rather than straight-edged ones. The design approach is based on the condition that the cutting edge lies along a straight generatrix of a hyperboloid, allowing the formation of a curved profile in the axial section with deviations from the involute remaining within permissible tolerances. The paper presents a methodology for determining the hyperboloid parameters to substitute the involute profile. The dependence of profile deviation from the involute is studied as a function of the outer diameter of the disc cutter. According to the computational results, in order to reduce involute deviation when using such profile substitution, it is necessary to employ four or more hyperboloid segments with varying parameters. The developed cutter design, based on straight-edged inserts without using profiled ones, significantly reduces tool manufacturing cost. The proposed cutter design is particularly suitable for machining large-module gears, where the cost of complex-shaped profiled inserts is significantly higher than that of straight-edged ones, thus reducing both operational expenses and machining costs for large-module gears.