OBRABOTKAMETALLOV technology Vol. 26 No. 2 2024 Fig. 11. Process flow diagram of measuring the surface roughness of a specimen after milling (see Fig. 8). For measurements and data processing of the initial roughness profile, the technique according to EN ISO 4288 was used. The data obtained during the registration process were processed using the classical provisions of mathematical statistics and experimental planning, and STATISTICA software was used to automate calculations. Results and discussion Below are the results of a study of milling machining of a steel 0.12-Cr18-Ni10-Ti (AISI 321). Measurements of the roughness parameter Ra depending on the milling modes and the specimens build direction are shown in Table 6. The milling width was assumed to be B = const = 7 mm with a plate thickness of h = 8.5 mm, i.e. the teeth of the mill at its end were always involved in machining. The minute feed of fmin varied under other identical cutting conditions (machining modes). The least squares method was used to plot graphs based on empirical data. All figures took into account the changes in the largest magnitude of these forces (see Fig. 12–14). Graphs of the change in the feed force Ph (the direction of the force Ph acts along the feed direction vector) and the lateral force Pv (the direction of the force Pv is perpendicular to the direction of the feed vector) with a change in the feed per minute fmin are shown in Fig. 12, and Fig. 13 shows graphs of the change in the axial force Px (acts along the axis of the mill, i.e. at the end milling – vertically), and for comparison, a graph of the change in the lateral force Pv is also placed on this field. In Fig. 13, the Px max along graph has an inflection when feed fmin = 240 mm/min. We believe that it is possible to simplify the nature of this graph and draw a straight line through all four points (line 4 in Fig. 13), taking into account the insignificance of the error under this assumption. The study of the influence of the milling depth t on the cutting forces showed a direct proportionality of the forces Ph from the milling depth (Fig. 15).
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