RESEARCH DEVELOPMENT OF CONTACT DEFORMATION STRESSES WHILE ROLLING

Abstract

The method of determination of contact normal and tangential stresses during rolling is considered, taking into account the development of deformation over time. There are many methods for determining the contact normal and tangential stresses, but they all consider the distribution along the strain boundary. This approach to solving problems does not allow to take into account the uneven deformation in the transverse direction and the influence of lateral non-contact zones adjacent to the actual deformation center. These factors should be taken into account when determining the tangent and normal stresses when rolling in calibers with different ratios of geometric shapes and rolling billet. Also, existing methods of determining contact normal and tangential stresses do not take into account the development of deformation over time. Deriving the equations that determine the deformation force of the friction force and pressure, it was assumed that the normal to the plane would not coincide with any of the axes of the coordinate system, and the inclined platform was considered as an inclined section in the parallelepiped voltage across the edges of the volume, which is distributed uniformly. The obtained formulas for determining the normal and tangent contact stresses in the deformation zone take into account rolling in calibers with different ratio of geometric shapes and rolling billet, characterize the dynamics of change of the deformation cell in time. The paper deals with rolling of AK6 alloy workpieces having Ø25x150 mm dimensions in oval caliber, with a height of 13 mm and a width of 29 mm and calculated normal and contact stresses. The plots of normal and tangent stresses show a change in the value of stress with increasing contact area and deformation time. The results of studies of normal and tangent stresses show a change in their values with increasing contact area and deformation time. When checking the proposed method, the discrepancy between the results of the theoretical calculation and the experimental data is not more than 4%, which confirms the possibility of using the method to determine the contact normal and tangential stresses during rolling.