OBRABOTKAMETALLOV technology Vol. 25 No. 2 2023 a b Fig. 5. Characteristic curves Kc = f(ρ;Θ): a – quadratic; b – linear with the help of the specified program, mathematical formulas describing the presented dependencies were established. In addition, using the STATISTICA 12 software, mathematical formulas describing the presented dependencies were established: Kc = 100.9073 - 0.2001ρ - 1.225Θ + 9.8915 ∙ 10 5ρ2 + 0.0013ρΘ - 0.0003Θ2; (2) Kc = -0.4622 + 0.0006ρ + 0.0071Θ (3) At the next stage of research, in order to determine the most accurate of the obtained dependencies, calculations were performed using formulas (2) and (3). The obtained values were compared with experimental values of Kc and the values of relative calculation errors were found. As a result, it was found that the error of calculations according to formula (2) modulo was from 1.49 to 41.16 %. The error of calculations according to the formula (3) modulo ranged from 3.58 to 28.68 %. Thus, the accuracy of calculations according to formula (3) is 1.44 times higher than according to formula (2). The evaluation of formula (3) shows that the constant coefficient for the variable ρ is significantly less than the coefficient for the variable Θ: by 11.83 times. This indicates the higher importance of the wetting edge angle when calculating the coefficient Kc Therefore, finding out the dependence Kc = f(r) is impractical, and the previous purpose of the research was to find out the dependence Kc = f(Θ). The constructed graph is shown in figure 6. The dependence shown in figure 6 is approximated by a straight line. The formula describing the constructed line is also shown in figure 6. By comparing the calculated values of Club with the experimental values of Kc, the relative error of calculations was established: from 2.75 to 23.99 %. It should be noted Fig. 6. Characteristic curve Kc = f(Θ)
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