Browsing by Author "Tolkushkin A."
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Item COMPUTER MODELING AND INVESTIGATION OF THE DEFORMATION PROCESS IN CONVEX-CONCAVE AND TRAPEZOIDAL STRIKERS(2023-01-01) Volokitin A.; Naizabekov A.; Panin E.; Tolkushkin A.; Nurakhmetov D.; Yordanova R.; Volokitina I.; Arbuz A.The article presents the results of a comparative analysis of the deformation process in convex-concave and trapezoidal strikers using computer modeling by the finite element method in the Deform program. In both designs, two variants are considered - with an equal and unequal ratio of the protrusion to the depression. For comparative analysis, equivalent stresses and strains, energy - power parameters are considered. Also, on the basis of computer modeling, the analysis of the microstructure evolution during the deformation in convex - concave and trapezoidal strikers was carried out. In the course of computer modeling, some advantage of the design of convex - concave strikers in comparison with trapezoidal strikers was proved.Item DESIGN IMPROVEMENT OF THE STEP-WEDGE DIES AND EXPERIMENTAL STUDY OF THE FORGING PROCESS OF 45 STEEL BILLETS(2024-01-01) Tolkushkin A.; Naizabekov A.; Panin E.; Yordanova R.; Shvarts D.; Tsyba P.; Volokitina I.; Rovin S.; Esbolat A.In this paper, a forging tool of a new design is proposed, which allows to implement shear and alternating strain in the entire volume of the deformed billet with a smaller change in its initial dimensions. To confirm the effectiveness of the proposed new forging tool in obtaining billets and forgings of the plates and slabs type of the required quality, a laboratory experiment was conducted. During the laboratory experiment, the forging of billets made of the steel 45 was carried out in such forging tools as step-wedge dies of two different variants (proposed and previously known) and in step dies. Analysis of the shape change of billets and the evolution of the microstructure of steel after two deformation cycles showed that the use of the step-wedge dies with a wedge protrusion on the upper die and a wedge cavity on the lower die is more promising for forging billets and forgings of the plates and slabs type with a given level of mechanical properties, since it allows to obtain a fine-grained structure with a smaller change in the initial dimensions of the billet.Item Development and Computer Simulation of the New Combined Process for Producing a Rebar Profile(2023-01-01) Lezhnev S.; Naizabekov A.; Panin E.; Tolkushkin A.; Kuis D.; Kasperovich A.; Yordanova R.The study presents results of computer simulation by finite elements method of a new metal forming process combining the deformation of a billet with round cross-section on a radial-shear rolling mill and subsequent billet twisting in a forming die with a specific design. To analyze the efficiency of metal processing, the main parameters of the stress-strain state are considered: effective strain, effective stress, average hydrostatic pressure, and Lode-Nadai coefficient. The maximum value of effective strain up to 13.5 is achieved when a screw profile on the billet in the die is forming, which indicates an intensive refinement of the initial structure of the billet. During combined process, the nature of the deformation changes in the transverse direction from the axis of rotation to the surface. The central area of the billet is under the action of tensile stresses. In the peripheral part, compressive stresses grow. In the surface area, Lode-Nadai coefficient is 0.1 approximately, which indicates the high level of shear strain.Item EFFECT OF THE LIMITING DEFORMATION ZONE UNDER CONDITIONS OF ASYMMETRIC LOADING DURING ROLLING OF MEDIUM THICKNESS STRIPS(2024-01-01) Chigirinsky V.; Naizabekov A.; Lezhnev S.; Kuzmin S.; Panin E.; Tolkushkin A.; Volokitina I.; Yordanova R.; Knapinski M.The aim of the work is to develop a physical and mathematical model of the process under complex asymmetric loading in conditions of single-area and two-area deformation zone during plastic processing of medium-thickness strips. The stress state in case of loss of stability during rolling of strips of medium thickness was investigated. The patterns of changes in the stress state of the strip under conditions of reach of the limiting deformation zone, as well as the effects of plastic shaping determined by a decrease in contact stresses under conditions of increasing deformation loading, are revealed. The described method is a visual approach to assessing the stress state of a plastic medium under conditions of complex interaction and asymmetric loading.Item Finite Element Modeling of ECAP-Linex Combined Process of Severe Plastic Deformation(2023-01-01) Panin E.; Volokitina I.; Volokitin A.; Naizabekov A.; Akhmetova G.; Lezhnev S.; Tolkushkin A.; Esbolat A.; Yordanova R.The paper presents theoretical studies of a new deformation process combining the stages of equal-channel angular pressing (ECAP) and the ``Linex``scheme. For correct finite element modeling of the process, a technique with sequential input for the calculation of conveyor links is presented. To analyze the efficiency of metal processing, the main parameters of the stress-strain state are considered: equivalent strain, equivalent stress, and average hydrostatic pressure, as well as the deformation force on the main elements of the combined process: pulley, matrix, and conveyor link. To analyze the resulting deformation forces, the stages of pressing in a matrix and compression by a chain conveyor were separately considered. Equations for determining the forces acting on the drive pulley, ECA matrix, and the chain element link were obtained. Comparison of values showed that the force values in the calculation and simulation have a high level of convergence. In all three considered details, the difference value did not exceed 10%. The variational modeling allowed to determine the optimal values of the main technological and geometric parameters of the process.