Abstract
The object of study is the stress-strain state of the steel strip when rolling in special convex-concave rolls. The work solves the problem of the evolution of stresses and deformations during combined rolling-bending, limiting the prediction of limit states and the choice of rolling modes in rolls of unconventional geometry. It was found that with an increase in equivalent deformation from 0 to 0.358, tangential deformation increases from 0 to 0.875, and radial deformation changes from 0 to –0.803, with a decrease in thickness under the influence of compressive load. Axial deformation reaches a maximum (about 0.140) at the deformation stage and becomes negative at the final stage due to redistribution of deformations during combined rolling-bending. The tangential stress coefficient increases from 0.500 to 2.716, and the axial coefficient decreases from 0.500 to –1.955, showing a natural change in the stress state. Analysis of analytical calculations with experimental data shows discrepancies of results not exceeding 5–7%. Large degrees of deformation provide high prediction accuracy compared to the theory of small elastoplastic deformations. The obtained results justify the geometry of convex-concave rolls, in which tangential tension and radial compression is accompanied by redistribution of axial deformation and leads to the formation of a uniform stress-strain state in the deformation zone. This applies to low carbon steels, which mechanical properties are close to those of 08kp steel (DC01 according to EN 10130/AISI 1008), under isothermal rolling conditions with strip contact with rolls and deformation degrees not exceeding ε = 0.358. This approach allows to increase the stability of the technological process, predict the limit states of deformation and improve the quality of strips in industrial conditions