Power Conditions of Rolling in Universal Calibers of Modern Rail and Structural Steel Mills

Development of a rolling stock, an increase in the speed of transportation, the traffic density of highways and their length requires constant improvement in the technology of production of railway rails. Modern rail and beam mills incorporate a continuously reversible group of stands, which includes universal stands. Rolling of rail profiles in universal calibers is fundamentally different from rolling in two-roll calibers. Currently, it is not well studied both in theoretical and practical terms. The conditions for the implementation of the rolling process in universal calibers with a pair of non-driven rolls are determined, considering the values of active (reserve) friction forces acting from the side of the drive rolls, and reactive forces from the non-driven rolls and roll fittings. Using the energy balance method, the problem of determining the backup force required for deformation in non-driven rolls is solved. When solving the equation for the balance of forces in the deformation zone formed by the drive rolls, the reserve of friction forces is determined, which largely determines the possibility of the rolling process. Theoretical dependencies are obtained for estimating the power balance during rolling in universal calibers of modern rail and beam mills, considering the reserve of friction forces provided by the drive rolls and the support required for deformation in the non-driven rolls. Information about the force conditions in a universal caliber is necessary to analyze its rolling process under various deformation modes and to refine the extraction coefficients for the elements of the resulting profile. Dependences are proposed that allow estimating the consumption of the friction force reserve for the operation of the roller fittings, which serves the universal caliber. The well-known formula of A.I. Tselikov and A.I. Grishkov to determine the broadening in relation to rolling in universal calibers with two non-driven rolls was clarified. The effect of support from non-driven rolls on the change in the size of the sole and head of rail profiles is noted.