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1

The innovative post-weld finishing method and non-standard cutting tool for carrying out this method

Dvirna Olha

Acta Mechanica et Automatica

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2024

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Vol. 18, no. 1

22--28

EN

The most common method of post-weld finishing is grinding with an abrasive tool. This finishing method leads to the occurrence of faults on the treated surface: locations missed or hardened twice, structural notches and stretching residual stress in the surface layer. The faults mentioned lead to the creation and development of ordinary as well as fatigue cracks, seizing or other damage. In addition, grinding is a process that often involves manual labour, which significantly increases the time required for finishing the procedure. Moreover, it is impossible to automate this process. Also, grinding is a process that is damaging for both people and the environment. In contrast to grinding and other processes of post-weld surface finishing, the innovative method, which is the subject of this article, does not have the faults and inconveniences of the previously mentioned techniques. The post-weld surface finishing method by moving of the innovative multi-edge cutting tool along the weld bead is presented in this article. In this method, machining allowance is treated as the weld bead height, which is flush-removed with the base material in one step during one pass of the cutting tool. The adjacent teeth height of changing and increasing according to the direction of feed and the difference in height between the first and last teeth are equal to the weld bead height. The number of cutting teeth necessary to flush-finish the weld bead with the base metal surface depends on the difference in the first and last teeth height and how it is divided. The tooth length is greater than half of the distance between the adjacent cutting teeth, which enables finishing the heterogeneous post-weld surface with many defects and increased hardness. The innovative method is characterised by short machining time of the weld bead and provides an accurate, efficient and economical process.

2

Technological methods of ensuring the reliability of lock connections in marine gas turbines

Dvirna Olha, Zembrzuska Natasza

Journal of KONBiN

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2022

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Vol. 52, iss. 3

149--163

EN

The article presents the test results of the surface quality parameters after broaching of heat-resistant steels of grades: 1.7335 (13CrMo4-5) and 1.4841 (X15CrNiSi25-20). The aim of the work is to determine the technological methods of obtaining the lowest treated surface roughness, surface layer hardening and the elimination of surface defects after broaching. To investigate the influence of cutting conditions (cutting speed, tool geometry and feed) on surface roughness and hardness, the physical modeling method of the broaching was used. As a result of the research, recommendations for improvement of the main parameters of the surface layer quality when broaching samples from selected grades of heat-resistant steels.

PL

W artykule przedstawiono wyniki badań parametrów jakości powierzchni po przeciąganiu stali żaroodpornych gatunków: 1.7335 (13CrMo4-5) i 1.4841 (X15CrNiSi25-20). Celem pracy jest określenie technologicznych sposobów uzyskania najmniejszej chropowatości obrobionej powierzchni, korzystnego poziomu umocnienia warstwy wierzchniej i eliminacji defektów powierzchniowych po obróbce skrawaniem. Aby zbadać wpływ warunków skrawania (prędkości skrawania, geometrii narzędzia i prędkości posuwu) na chropowatość i umocnienia powierzchni, zastosowana została metoda modelowania fizycznego procesu przeciągania. W wyniku badań opracowane zostały rekomendacje dotyczące podniesienia głównych parametrów jakości warstwy wierzchniej podczas przeciągania próbek z wybranych gatunków materiałów żaroodpornych.

3

Rational Liquid Cooling Systems of Internal Combustion Engines

Moshentsev Yuryi, Gogorenko Oleksiy, Dvirna Olha

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 1

158--169

EN

The scheme of the cooling system is considered, which can be the basis for creating the most efficient cooling systems for IC engines of any purpose. It is assumed that the use of any other scheme is devoid of a rational basis. The scheme consists of two connected circulation circuits, in one of which the coolant flow rate is an order of magnitude less than in the second. The engine is included in a circuit with increased coolant flow. All heat exchangers are in the second circuit. Rules for the formation of such systems are formulated. The basis of the method for calculating such systems is considered. It is indicated that the flow rate through each heat exchanger must be determined by calculation to ensure the maximum efficiency of the cooling system. The considered scheme allows to provide the maximum possible depth of charge air cooling, if its temperature is not specified, or to ensure the minimum cost and compactness of the cooling system, if this temperature is known. The scheme allows regulating the temperatures of the cooling fluids of the system with all kinds of changes in the engine operating conditions and the ambient temperature.

4

Possibilities for Improving the Cooling Systems of IC Engines of Marine Power Plants

Moshentsev Yuryi, Gogorenko Oleksiy, Dvirna Olha

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 3

183--192

EN

Modern cooling systems for large ships are quite complex. As a rule, such systems are common (combined) for the main and auxiliaries engines. With the auxiliary engines running constantly, even when parked, this system design allows to keep it warm and ready for a quick start of the main engines at any time. Currently, various schemes of such systems are used, including those that are irrational from our point of view. At the same time, there are systems whose schemes are quite consistent with our idea of the rational forms of such structures. It is important to note, and it is saying about it in an article, that such schemes may have a number of significant differences, but at the same time they will comply with the rationality principle if certain rules for the formation of such systems are followed. These schemes will have close compactness. It is also important that there is the possibility of further improvement of such schemes based on certain rules. This improvement is possible due to the introduction of additional heat dissipaters and the organization of appropriate chains of heat sources and heat dissipaters. The article discusses various options for rational schemes of the cooling system for the same ship power plant, as well as the possibility of further improvement of this scheme. It is shown that an increase in the number of coolants of the internal circuit coolant from one to three can reduce the total mass of the heat exchanger cores by 18 %.

5

Dynamic Processes Modeling in a Peristaltic Pump with a Hydraulic Drive for the Bingham Fluid

Shatokhin Vladimir M., Ivanchuk Yaroslav V., Dvirna Olha, Veselovskaya Natalia, Jurczak Wojciech

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 4

256--269

EN

At present peristaltic pumps are widely used in many branches of industry and national economy. Simplicity of construction, processability and possibility of pumping liquids with big quantity of solid particles are the main advantages while using peristaltic pumps. Therefore development of methods of rational choice of parameters at designing of peristaltic pumps is the actual problem. To develop universal mathematical models of dynamic processes in peristaltic pumps for definition of rational technical parameters. In dynamic processes we propose to use differential equations of motion in the Lagrange form, where the angle of rotation of the pump rotor is taken as a universal coordinate. Mathematical model of dynamic processes in peristaltic pump with hydraulic drive has been created on the base of differential equation. The function of resistance forces caused by gravity forces of mixture particles in the hose reel has been determined. On the basis of the non-linear model of the resistance forces to the flow of the fluid Bingham method of constructing the dependence of the pressure drop on the angular velocity of the rotor to determine the resistance forces to the flow of the fluid has been proposed. The result of dynamic processes simulation is the determination of interrelationship of technological parameters of the device functioning: the velocity of the medium and pump performance is increasing at reducing the length of the diverting hose and reducing the height of its rise; a significant influence on the average speed has plastic viscosity of the environment; a significant change in the yield strength has an insignificant impact on the speed.

6

The physical modelling of high speed broaching of the heat-resistant steels for studies surface layer quality

Dvirna Olha

Journal of KONES

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2019

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Vol. 26, No. 3

23--29

EN

The main idea of the work is to create a physical model of high speed broaching heat-resistant materials is used to study the parameters of the surface layer quality. Modelling is a method of mediated cognition, in which the object under study is in some correspondence with the model, and the object-model is capable in some way or another to replace the original at some stages of the cognitive process. Physical modelling is primarily distinguished by the fact that studies are conducted on models with physical similarity, i.e. preserving completely (or at least partially) the nature of the phenomena. The work of the broach can be likened to the work of a number of planning cutter displaced relative to each other by a small amount, which is called lifting (feed per tooth). Therefore, for experimental work, a planning cutter of a special geometric was designed and manufactured – a physical model of a broach, in which geometric, mechanical and dynamic similarity is realized. The article also presents an experimental justification for the use of the created physical model in the study of the surface quality parameters of the, tab grooves of turbine and compressors disks made of heat-resistant materials.