Browsing by Author "Leshchenko, O. I."

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Analytical Studies of the Influence of the Technological Parameters of the Process of Pulling the Strip Through the Bending-Stretching Device on the Change of the Energy-Force Parameters of the Process
(Інститут чорної металургії ім. З. І. Некрасова НАН України, м. Дніпро, 2024) Razdobrieiev, V. H.; Kluychnikov, K. Yu.; Palamar, D. H.; Leshchenko, O. I.; Ivanov, Oleksandr P.
ENG: It is impossible to imagine the modern development of technology without the use of metal products, including wire products, which are subject to high requirements in terms of variety and quality, and to the production processes, for example, wire of a fashioned profile, the flexibility of technology, high efficiency and economy, labor safety and automation. One of them is the process of drawing metal in roller dies, which combines the features of two methods of pressure metal processing - rolling and drawing. The main working tool when applying the drawing process in roller dies is a roller die with non-driven working rollers. The main drawback of the roller dies method is the presence of traction force. Stretching stresses in combination with a decrease in the plasticity of the metal during the drawing process can lead to the destruction of the rolled product. This limits the assortment of profiles, the total crimping in one of transition. It is possible to increase the plasticity of metal in two ways - thermal and mechanical. The thermal method, which is widely used in industry, requires significant energy consumption. At the same time, previous studies, which were carried out including in the ISI NASU, showed that it is possible to increase the plasticity of the metal by means of alternating sign deformation of the profiles, using, for example, equipment for straightening profiles or a scale breaker. The purpose of analytical research is to establish the dependence of the influence of the technological parameters of the drawing process in a roller drawing machine combined with the pulling of strips through a device for bending with tension (DBT) on the change of the energy parameters of the process based on the developed mathematical model. Analytical studies of the influence of the technological parameters of the DBT were carried out for the case of deformation of the initial workpiece of round cross-section with a diameter of 5.90 mm from low-carbon steel of the St.08 brand in a double-roll roller die with smooth rolls, combined with DBT in the conditions of the laboratory base of the pressure metal processing department of the Iron and Steel Institute of the Z.I. Nekrasov of NASU. On the basis of the revealed regularities, the dependences of the energy-force parameters of the process of drawing in a roller die, combined with the drawing of strip through the DBT, on the influence of the main technological parameters were obtained. It was established that an increase in the distance between of the axes rollers of the DBT at a constant value of the movement of the axis of the pressure roller of the DBT in the vertical direction leads to a decrease in the angle of coverage of the roller by the strip. It has been established that at a constant distance between the axes of the DBT rollers, when the amount of movement of the axis of the DBT pressure roller increases vertically, on the contrary, the values of the angle of coverage of the roller by the strip increase. It is shown that an increase in the number the rollers of DBR leads to an increase in both the pulling force of the strip and the normal component of the force acting on the trunnion of the rollers of the DBT. It was determined that the most significant influence of the height of the stretched strip and the radius the rollers of the DBT on the pulling force occurs in the range of relations R/h≤10. It was established that an increase in the total degree of preliminary deformation in the roller die and sign-changing deformation in the DBT of the strip leads to an increase in the value of the pulling force.
Modeling the Process of Alternating Deformation of a Strip-Type Profile in a Three-Roller Bending-Tensile Device
(Інститут чорної металургії ім. З. І. Некрасова НАН України, 2026) Razdobrieiev, V. H.; Kluychnikov, K. Yu.; Palamar, D. H.; Leshchenko, O. I.; Ivanov, Oleksandr P.
ENG: The use of high-precision profiles in modern mechanical engineering is of great importance in terms of improving the quality of manufactured products and significantly reducing the cost of their production. In Ukraine, the production of high-precision profiles is extremely limited, and the production of strip-type profiles is completely absent. In world practice, the production of strip-type profiles is possible in various ways: hot rolling, hot pressing, cold rolling, or drawing in monolithic or roller drawing mills. Roller dies for the production of shaped profiles have an advantage over monolithic dies, as a greater amount of crimping is possible in one pass. In addition, drawing in roller drawing machines takes place in non-driven rollers in combination with environmentally friendly heat treatment methods without the use of harmful cooling media in the form of lubricants, lead melts, salts and acids. At the same time, the peculiarities of the conditions of plastic equilibrium of the metal of the deformation center during the flattening of a round billet by drawing in roller draws inhibit the development of new profiles, including strip-type profiles with a ratio of their width to thickness of more than two. This is due to the fact that the uneven compression of the wire blank leads to an uneven distribution of stresses across the profile cross-section: in the middle part – compression, at the edges – tension and the presence of tensile force increases the areas of action of tensile stresses and their magnitude in the volume of the deformation center and, ultimately, under certain conditions, causes a significant decrease in plasticity and destruction of the edges of the finished profile. There are two ways to increase the plasticity of a metal – thermal and mechanical. The thermal method, which is widely used in industry, requires significant energy consumption. At the same time, previous studies, including those conducted at the ISI NASU, showed that it is . possible to increase the plasticity of metal by means of alternating deformation of profiles, using, for example, equipment for straightening profiles or a scale breaker. At the same time, the results of specific studies of the influence of the parameters of the process of alternating metal deformation on the magnitude of stresses and the nature of their distribution over the cross-section of a strip-type profile are absent in the considered publications. The purpose of the research was to consistently analyze the stress state of the metal throughout the actual deformation center, taking into account the external zones, using a developed and tested mathematical model for calculating the stress-strain state of the metal. It has been established that the mechanism of residual stress occurrence is due to the magnitude of plastic deformation and the inhomogeneity of the distribution of deformations over the thickness of the profile during alternating deformation during its pulling through the DBT. According to the modeling results, it was determined that the maximum values of residual longitudinal stresses formed along the profile cross-section after leaving the DBT are 1.4 times less, regardless of the sign of the stresses, compared to the maximum longitudinal stresses formed under the pressure roller. It is shown that the maximum level of plastic deformations is observed at the beginning of alternating deformations in the DBT device with a decrease in their level at the exit from the DBT, which provides a decrease in the values of residual stresses and potential energy in the column made of St.08 steel.