OBRABOTKAMETALLOV Vol. 24 No. 3 2022 TECHNOLOGY Fig. 11. The dependence of a grinding wheel rotation speed on the force of its pressing against rail at optimal values α = 45° and e = 88.4 mm: 1 – STU method; 2 – HSG method Conclusion The theoretical analysis of two methods of passive grinding of rails using grinding trains allows drawing the following conclusions: 1. The technology of passive grinding, implemented by the HSG method, has a higher productivity and energy effi ciency of the machining process in comparison with the STU method due to the higher rotation speed of the grinding wheel with equal forces of pressing it to the rail. 2. The STU passive grinding method is distinguished by a wide range of changes in both the rotation speed of the grinding wheel and its pressing force. This makes it possible, at the same speeds as the HSG method, to achieve a higher speed of grinding the rail surface and to achieve greater metal removal due to a stronger pressing of the grinding wheel to the rail. 3. The presented approach makes it possible to form a database of optimal modes for passive grinding of rails, on the basis of which it is possible to carry out a well-reasoned choice of pressing forces of the grinding wheel to the rail based on the required metal removal and the specifi ed speed of the grinding train. 4. The analysis carried out is of an idealized nature, which does not take into account a number of signifi cant parameters that have a signifi cant impact on both the physical processes of interaction between the grinding wheels and the rail, and the machining process itself. At the same time, it gives a general comparative idea of the effi ciency and possible productivity of the passive grinding methods under consideration. 5. A promising direction for further research in the fi eld of passive grinding of rails is to expand the theory of interaction of grinding wheels with a rail by including in the mathematical model such parameters as the contact area of the grinding wheel with the rail, the structure and grain size of the abrasive tool, and metal removal. The experimental and theoretical determination of the numerical values of the coeffi cient of interaction of the grinding wheel with the rail λ can also be considered a key task. References 1. Jeong W., Hong J., Kho H., Lee H. Rail surface quality analysis according to rail grinding on operational railway track. Journal of the Korean Society for Railway, 2021, vol. 24, iss. 10, pp. 852–860. DOI: 10.7782/ JKSR.2021.24.10.852. 2. Lundmark J. Rail grinding and its impact on the wear of wheels and rails. Licentiate Thesis, 2007. Available at: https://www.diva-portal.org/smash/get/diva2:990239/FULLTEXT01.pdf (accessed 03.08.2022).
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