Serhii Shevtsov
@dgma.donetsk.ua
Department of Mathematics and Modeling
Donbas State Engineering Academy
RESEARCH, TEACHING, or OTHER INTERESTS
Mathematics, Modeling and Simulation, Engineering
Scopus Publications
Scopus Publications
Oleg Markov, Serhii Shevtsov, Natalia Hrudkina, Vitalii Molodetskyi, Anton Musorin, and Volodymyr Zinskyi
Private Company Technology Center
The object of this study is the technological process of manufacturing parts such as artillery shells using pressure treatment methods. The work is aimed at solving the current scientific and technical task to improve the technological processes for manufacturing parts such as cartridge cases based on the use of a tangential rolling operation with a friction tool, which ensures the production of hollow products with a bottom. Using the finite element method, modeling of the bottom rolling processes was carried out, which made it possible to establish the effective geometry of the processed workpieces and their heating temperature. Recommendations have been devised for the design of new technological processes for roughing bottoms, which consist of determining the wall thickness of the workpiece before deformation, the heating temperature of the workpieces, and the amount of supply of the workpiece to the friction tool. The resulting recommendations were verified by experimental studies. Roughing of spherical bottoms should be carried out for pipes with a relative wall thickness (D/s) in the range of 15...20, the homologous heating temperature should be 0.8, and the relative feed of the workpiece into the friction tool should be 0.9. Testing the established relationships under laboratory conditions confirmed the recommendations for changing the shape of spherical bottoms during the roughing process. The results of metallographic studies on full-scale products confirm the results of the theoretical study. It is recommended to use this technique for products that have an axial hole (artillery shells, hydraulic cylinders, etc.), which will allow removing axial defects in the bottom after drilling the axial hole. The results could be used at machine-building enterprises in the manufacture of dual-use parts
Natalia Hrudkina, Leila Aliieva, Oleg Markov, Dmytro Kartamyshev, Serhii Shevtsov, and Mykola Kuznetsov
Private Company Technology Center
It has been proposed to use the developed triangular kinematic module 2a with a curvilinear sloping boundary as an axial one, making it possible to describe the character of metal flow in the reversal zone to radial extrusion. Based on the energy method, we have derived the magnitudes of deformation force power inside the built kinematic module 2a, the power of friction forces at the border of the contact between a blank and a tool, and the power of cut forces with adjacent kinematic modules. The result is the obtained analytical expression of the reduced pressure for the deformation of the axial triangular kinematic module 2a with a sloping boundary, whose shape depends on the parameter α. We have analyzed the possibilities of optimizing the reduced deformation pressure for the parameter α under different ratios of geometric parameters of the module and friction conditions. Taking into consideration the shape of the adjacent kinematic module 3a, it has been proposed to use the resulting reduced pressure dependences to calculate the power modes of the combined sequential radial-longitudinal extrusion processes with the developed radial component of metal flow. A comparative analysis has been performed of the estimation schemes EM-2a with the developed axial triangular kinematic module 2a and EM-2 with the use of the axial rectangular kinematic module 2 and experimental data from modeling the process of combined radial-direct extrusion with expansion. The data on a deformation effort derived from the EM-2a scheme (with the developed triangular module with a curvilinear boundary 2a) and EM-2 exceed those experimentally obtained by 12‒15 % and 15‒20 %, respectively. This confirms the rationality of using the developed axial kinematic module 2a with a curvilinear boundary instead of an axial rectangular kinematic module when modeling processes of the sequential radial-direct extrusion with the developed radial component of metal flow. The resulting dependences of the reduced pressure of the module 2a deformation can be built into other estimation schemes of successive radial-longitudinal extrusion processes. As a result, the decrease in the obtained power parameters of the process could amount to 7‒10 % relative to the schemes involving the axial rectangular kinematic module 2
Natalia Hrudkina, Leila Aliieva, Payman Abhari, Mykola Kuznetsov, and Serhii Shevtsov
Private Company Technology Center
The possibilities of using and embedding kinematic trapezoid modules with curvilinear boundaries of different shapes were explored. Based on the energy method, the generalized formulas for calculating the power of deformation forces inside the axial trapezoidal kinematic module were derived. Different types of selecting the functions that describe a curvilinear boundary of the axial trapezoidal module were identified. We have analyzed the possibilities of using known techniques for the linearization of integrand dependences in order to calculate the power of deformation forces when it is impossible to obtain a given magnitude in the form of an analytical function. The ways to derive engineering formulas for the computation of components of reduced pressure inside an axial trapezoidal kinematic module were proposed. Based on the energy method, we obtained formulas for the calculation of a step-by-step change in the shape of a semi-finished product under assumption within the axial trapezoidal kinematic module. We modeled the process of combined extrusion of hollow parts with a flange and established regularities in shape formation depending on geometrical parameters. The data about a step-by-step change in the shape of a semi-finished product during deformation were obtained. A comparative analysis of calculation schemes for the rectilinear trapezoidal kinematic module and with a curvilinear boundary under assumption within the studied module was performed. It was confirmed that the reported ways for obtaining engineering formulas, as well as the algorithm for the calculation of processes of combined extrusion that is based on them, simplify the development of technological recommendations. This applies both to determining the force mode of extrusion and preliminary assessment of a change in the shape of a semi-finished product with the possibility to control a metal outflow in the process of deformation
Oleg Markov, Vitalii Zlygoriev, Oleksiy Gerasimenko, Natalia Hrudkina, and Serhii Shevtsov
Private Company Technology Center
We propose a forging method for forgings, which implies the upsetting of workpieces with concave facets. A procedure for the theoretical research has been devised aimed at studying the mechanism of closure of artificial axial defects in workpieces. The study was performed based on a finite element method. The key examined parameter was the depth of the concave facets in a workpiece. This parameter varied in the range 0.75; 0.85; and 0.80. The angle of the concave facets was 120°. The results of the theoretical study are the following distributions: deformations, temperatures, and stresses in the body of a workpiece in the process of upsetting the workpieces with concave facets. Based on these parameters, we established an indicator of the stressed state in the axial zone of the workpiece. In order to verify the theoretical results obtained, a procedure for experimental research has been developed. The study was performed using the lead and steel workpieces. The results of the theoretical study allowed us to establish that the effective depth of the concave facets is the ratio of diameters of protrusions and ledges equal to 0.85. At this ratio there occurs the intensive closure of an axial defect. This is due to the high level of compressive stresses when upsetting the workpieces with concave facets. We have established the effective degree of deformation at which the intensive closure of defects takes place. Also established are the distributions of deformations for the cross-section and height of the workpiece, as well as a change in the indicator of the stressed state in the process of upsetting workpieces with concave facets. The closure of axial defects has been confirmed by experimental study using lead and steel samples. The new technique for upsetting workpieces with concave facets has been implemented. The results of ultrasonic testing have allowed us to establish that the obtained parts do not have internal defects, which exceed the requirements of the European standard SEP 1921. Our research has led to the conclusion of the high efficiency of the proposed new method for upsetting workpieces with concave facets, which implies the improvement of quality of the axial zone of large forgings when using a given technique.