OBRABOTKAMETALLOV technology Vol. 25 No. 3 2023 These values are valid for nominal values of the grinding wheel pressing force for the range of current loads in the motor windings 37–53 A. In the future, when testing prototypes of industrial electric motors, these dependencies need to be clarified. Evaluation of the quality of the polished surface by the roughness parameter (fig. 14) showed that the nature of the curve is similar to the dependence of the metal removal at the angles of inclination of the grinding motor (fig. 12). This is natural because the greater the angle of inclination of the grinding motor, the smaller the width of the grinding track, and the specific load on a single grain is greater. As a consequence, the introduction of abrasive grains into the surface being processed is greater, which gives greater metal removal and, accordingly, surface roughness. The effect of the speed of grinding trolley movement on the formed surface roughness can be seen in the graph shown in fig. 15: with an increase in the working speed of movement, the surface roughness increases. This is also due to the influence of the number of abrasive grains passing through the elementary surface of the rail being processed. The higher the speed, the fewer such abrasive grains will be and, consequently, the roughness will be greater. In addition, it should be noted that in all ranges of grinding modes used in the tests, the roughness of the formed surface did not exceed the values established by the regulatory documentation for Ra – 6 µm. Fig. 14. Surface roughness at the angles of inclination of grinding motor Fig. 15. Dependence of roughness of the machined surface on grinding modes Also in the tests, the presence of cauterization on the polished surface was visually assessed. The passages after which the cauterization is fixed are marked with a “+” sign in the corresponding column of Table 3. According to the marked passages, it can be established that the occurrence of cauterization occurs when the maximum loads that occur during grinding are exceeded. This is typical for metal removal exceeding 0.35 mm. Conclusions According to the test results, the following parameters of the working equipment of the rail grinding train being designed, implementing the technology of high-speed rail grinding, are established: 1. The pneumatic system of the rail grinding train should implement a pressing pressure in the range of 0.8–1 atm per grinding head to ensure the necessary pressing force of the grinding wheel to the rail 2,800–2,900 N. 2. The range of current loads during operation of the electric drive of the grinding head is 37–53 A. Taking into account the long-term operation of the electric drive, the parameters of the diesel generator set,
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