OBRABOTKAMETALLOV TECHNOLOGY Vol. 24 No. 3 2022 the probability of the grinding wheel turning. So, when the angle α is close to 90°, and the eccentricity e is close to zero, the rotation of the grinding wheels is practically eliminated and the process of machining the rail, according to its principle, passes into the usual bar grinding described earlier (Fig. 1). The reverse situation occurs when the value of the force Fr exceeds the value of the force Fg. In this case, the free rotation of the grinding wheel begins to dominate over the process of cutting the metal, and at the minimum values of the angle α and the maximum values of the eccentricity e, the movement of the abrasive tool actually turns into rotation-rolling without turning, in which the machining process does not occur. The point of intersection on the diagrams can be considered as a condition for optimizing the values of the angle α or eccentricity e for the relevant grinding methods, in which the most effi cient machining of the rail surface will be carried out with uniform rotation of the grinding wheel, excluding its salting loading and loss of effi ciency. Based on the condition Fr = Fg, the simultaneous solution of equations (6) and (7) for the HSG method shows that cosα = sinα, which corresponds to α = 45°, which can be considered the best value of the angle of rotation of the grinding wheel. A similar solution of equations (8) and (9) for the STU method shows that the best value of eccentricity e is determined by the dependence: a b Fig. 10. Graphs of variance in components of force action on a grinding wheel at Q = 500 N, λ = 1 and R = 125 mm: a – HSG method; b – STU method
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