Browsing by Author "Volokitina I."

Now showing 1 - 8 of 8
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    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.
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    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.
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    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.
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    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.
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    Recycling of metal scrap of ferrous metals using mini-mill of radial-shear rolling and drawing mill
    (2020-01-01) Lezhnev S.; Naizabekov A.; Panin E.; Volokitina I.; Turabaeva M.; Yordanova R.; Sal'ko O.
    Re-processing of scrap metal is one of the most important directions in the production of metals and alloys, as well as in the manufacture of various metal products. This activity is called the recycling. Recycling of scrap metal can be carried out, both by melting it, or by technology, currently gaining distribution in some metallurgical and engineering plants and which includes the processing of end-of-life metal products by hot forming. In this paper, the technology of recycling of ferrous metal scrap in the conditions of Akmola branch of JSC ``Kazvtorchermet``, in order to obtain high-quality commercial product in the form of bars of circular cross-section or wire, is proposed.
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    REDUCTION OF METAL CONSUMPTION OF ROLLED PRODUCTS
    (2023-01-01) Chigirinsky V.; Volokitina I.; Bozhko L.; Ovchynnykov O.; Yordanova R.
    Weight significantly affects the strength of products and technological parameters of production. Section weight determines temperature mode, power parameters of rolling, conditions of thin-walled section formation. In our solution, the central zone was lightened by transverse stiffeners. This made it possible to reduce the weight of the product while ensuring reliable performance characteristics. Wheels made of sections rolled in Rolling Mill 550 conditions successfully passed road and strain gauge tests.
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    Research of influence equal channel angular pressing on the microstructure of copper
    (2014-01-01) Lezhnev S.; Volokitina I.; Koinov T.
    The effect of equal-channel angular pressing (ECAP) in step die on the microstructure and properties of preheated copper is studied. It is found that the grain size after ECAP depends slightly on the preliminary thermal treatment, but the quenching applied decreases copper hardness values by 15 %, which in turn provides to decrease the pressing force during the first pass from 620 kN to 510 kN. The minimum average grain diameter reached in case of quenching alloy M1 at 700° C, ECAP in step die at room temperature and 6 cycles of deformation is 0.6 microns.
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    The effect of preliminary and final heat treatment in course of the combined ``rolling-pressing`` process realization on microstructure evolution of copper
    (2016-01-01) Lezhnev S.; Naizabekov A.; Panin E.; Volokitina I.; Koinov T.
    A number of new methods of pressure processing of metals aimed at obtaining sub-ultrafine-grained structure have been recently developed. Their basic principle refers to realization of a simple shear scheme deformation. One of the approaches is to press blanks in matrices of different designs, in equal-channel step die in particular. However, this method has a significant disadvantage - it cannot be used to deform lengthy billets. Furthermore, this method does not provide the continuity of the pressing process. To remove these shortcomings a combined ``rolling-pressing`` process using an equal channel step matrix with calibrated and smooth rolls is developed at the Department of ``Metal Forming`` at the Karaganda State Industrial University. This work investigates the impact of the process advanced. It focuses on the preliminary and final heat treatment during its implementation on the microstructure evolution and the mechanical properties of the copper alloy produced. The results indicate that the technology proposed can be recommended for implementation in production of blanks of ferrous and non-ferrous metals and alloys with ultrafine-grained structure and good mechanical properties.