Problems of Tribology = Проблеми трибології - 2024 рік

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https://elar.khmnu.edu.ua/handle/123456789/15926

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Modeling of contact stresses and evaluation of wear life of a valve mechanism guide with lubricating grooves
(Хмельницький національний університет, 2024) Holenko, K.; Vychavka, A.; Dykha, M.; Dytyniuk, V.
Valve guides are crucial for maintaining proper alignment, positioning, and valve stem clearance as it moves in the cylinder head. Valve bushings are subjected to load and sliding friction; with excessive wear of the guides, the engine begins to consume oil and the valve mechanism becomes noisy. This paper proposes the use of a special knurling to restore and increase the wear resistance of guide bushings. The profile tool is designed to restore valve guides by rolling a spiral groove on the inner surface of the sleeve. After applying this technology, a spiral oil-retaining profile remains on the surface of the sleeve bore. . Using the Solid model, the effect of changing the geometry of the guide bore by the lubricating grooves on the maximum and average stress indices in the guide-valve contact was analyzed. It was found that the maximum stresses of the model with grooves are lower than those of the model with a smooth guide surface. Based on the finite element model, the durability of the valve-guide pair with oil-retaining grooves was analyzed and it was determined how many cycles the contact surface of the guide can withstand. It was established that by reducing the contact pressure, the actual resource of the guide with grooves increased.
Wear resistance and lubricity of the spiral oil distribution profile of the valve guide sleeves of an internal combustion engine
(Хмельницький національний університет, 2024) Dykha, O. V.; Vychavka, A. A.; Dykha, M. O.
Valve guides are crucial for maintaining the correct alignment, positioning, and clearance of the valve stem as it moves in the cylinder head. When the guides are heavily worn, the engine begins to consume oil and the valve mechanism becomes noisy. Reliable lubrication of the inner surface of the guide bushing ensures the wear resistance of the valve-guide pair. This work proposes a special tool and technology for obtaining an oil-retaining profile on the inner surface of the valve guide, which increases the oil capacity of the surface, and therefore improves the lubrication conditions in the valve-guide friction pair. A gas labyrinth seal is created in the connection, which prevents oil from entering the combustion chamber. The surface of the bushing bore is strengthened due to the sealing of the surface. The results of wear tests of guide bushings with spiral oil-retaining grooves confirmed their effectiveness in terms of wear resistance. The wear rate of the bushings with grooves for the entire time range of the tests is on average 20% less than the wear rate of the bushings without grooves.
Dependence of wear intensity on the coating material of the hydraulic cylinder of the garbage truck’s sealing plate
(Хмельницький національний університет, 2024) Bereziuk, O.V.; Savulyak, V.I.; Kharzhevskyi, V.O.; Alekseiev, A.Ye.
The article is dedicated to the study of the influence of the coating material on the wear rate of the hydraulic cylinder of the mechanism of the garbage truck’s sealing plate. By means of a first-order planning of experiment with first-order interaction effects using the Box-Wilson method, an adequate dependence of the wear rate of the hydraulic cylinder of the mechanism of the garbage truck’s sealing plate on the coating material was determined. It is established that according to the Student’s criterion, among the studied factors of influence, the intensity of wear of the hydraulic cylinder of the mechanism of the garbage truck’s sealing plate is most affected by the iron content in the coating, the least – by the chromium content, and the nickel content affects only indirectly in interaction with the iron content. The response surfaces of the goal function – the intensity of wear of the hydraulic cylinder of the mechanism of the garbage truck’s sealing plate and their two-dimensional sections in the planes of the influence parameters are shown, which allow to clearly illustrate the specified dependence of this goal function on individual influence factors. The expediency of conducting further research to determine ways to further improve the wear resistance of the hydraulic cylinder of the mechanism of the garbage truck’s sealing plate is shown
Research on the wear resistance of the material cylinder of an automatic injection molding machine during plastics processing
(Хмельницький національний університет, 2024) Honchar, V. A.
The article presents experimental studies of the pressure in the material cylinder of the D3328 automatic injection molding machine when processing various plastics, as well as experimental studies of wear along the length of the material cylinder of the DB3328 automatic injection molding machine after processing PS 68-30 fiberglass. Specially designed strain gauge pressure sensors were used. Signals from the sensors were output to an oscilloscope through the amplifying equipment and recorded on an oscillogram. The magnitude and distribution of pressure along the length of the material cylinder will significantly affect the amount of wear of both the screw and the cylinder. It was established that the pressure in the material cylinder of automatic injection molding machines is distributed unevenly along its length. The nature of the pressure distribution along the length of the material cylinder when processing various materials: during the injection period, the maximum pressure occurs in the melt zone with a subsequent sharp decrease in the middle zone and a slight increase in the loading zone. At the same time, the nature of the pressure change for all materials is similar at a diametrical gap between the screw and the cylinder δ=0.17 mm. With an increase in the gap δ to 0.74 mm, the nature of the pressure distribution in the injection zone changes only when processing fiberglass, which is due to the partial ingress of glass fibers into the gap between the screw and the cylinder. Its magnitude and nature of the distribution along the length for different materials are different and depend on the physical, mechanical and rheological characteristics of these materials, the design of the screw and the technological modes of processing. The maximum pressure occurs in the melt zone during the period of material injection into the mold for 0.4-0.5 s.
The effect of manganese and carbon on the mechanical properties of the welded layer of the bucket teeth of the Hadfield steel excavator
(Хмельницький національний університет, 2024) Posonskyi, S.F.
The paper investigates the effect of the surfacing composition’s chemical structure (the manganese and carbon concentrations’ ratio) on the mechanical properties of the surfacing layer on Hadfield steel for increasing the durability of the products made from it, namely the excavator bucket’s teeth. Two criteria, namely the impact toughness and wear resistance of the coating, were chosen as optimization parameters. The assessment of the impact strength of the deposited coating was carried out on the Sharpie samples on the pendulum copra, and the wear test was carried out according to the Brinly-Haworth scheme in the conditions of samples’ abrasion with quartz sand. Wear resistance of Hadfield steel, containing 1.1% C and 13% Mn, was taken as a unit of wear resistance in these experiments. To determine the optimal coating modes, the active experiment with the application of mathematical planning methods was conducted. The obtained response surfaces and graphs of equal output lines make it possible to establish the level of studied factors’ influence on the optimization parameter. In order to analyze the influence of given factors on the optimization criteria, scatter plots with histograms were constructed, which make it possible to determine the rational values of the selected optimization criteria graphically - impact toughness and wear resistance of the coating.
Dependence of wear of friction pairs of the mechanism for loading solid household waste into a garbage truck on the characteristics of antifriction materials
(Хмельницький національний університет, 2024) Bereziuk, O.V.; Savulyak, V.I.; Kharzhevskyi, V.O.; Serdiuk, O.V.; Yavorskyi, V.Ye.
The article is dedicated to the establishment a regression dependence of wear of friction units of the mechanism of loading a garbage truck on the properties of antifriction materials. By using a first-order planning of experiment with first-order interaction effects using the Box-Wilson method, an appropriate regularity of wear of friction units of the garbage truck loading mechanism on the properties of antifriction materials has been determined. It is established that, according to the Student's criterion, among the studied factors of influence, the wear of friction units of the garbage truck loading mechanism is most influenced by the pressure in the friction zone, and the least – by the Brinell hardness of the antifriction material. The response surfaces of the objective function – wear of friction units of the garbage truck loading mechanism and their two-dimensional cross-sections in the planes of the influence parameters are shown, which allow to clearly illustrate the specified dependence of this objective function on individual influence parameters. It has been established that an increase in the pressure in the friction zone and sliding speed by 60% leads to an increase in the wear of friction units of the garbage truck loading mechanism during reverse motion by 6.3...34%, depending on the properties of antifriction materials. The expediency of conducting further research to determine ways to further improve the wear resistance of friction units of the mechanism for loading solid household waste into a garbage truck has been shown.
Methodology and results of the study of physical, mechanical and tribological characteristics of nitrided inner surfaces of long holes
(Хмельницький національний університет, 2024) Stechyshyn, M.S.; Dykha, O.V.; Stechyshynа, N.M.; Zdorenko, D.V.
Created control device physico-chemical and tribological characteristics of nitrided internal surfaces of long holes, which is a hollow pipe with radial holes made at a certain distance from its ends to ensure the ratio of the height of the center of the sample to the internal diameter of the pipe from 0 to 10 or more, which differs in that the height of the samples simulates the depth of the longitudinal holes, and the samples themselves to facilitate their fixation and to ensure the absence of electric spark discharge near the ends, they are installed with a certain tension. At the same time, the length of the cylindrical sample is equal to the thickness of the pipe wall.Thus, each sample is nitrided from two ends, which makes it possible to nitride from the outside and from the middle of the model at almost the same temperature, as well as to compare the results of nitriding of two surfaces (external and internal). At the same time, the difference in conditions is only in the location of these surfaces - external or internal. All other factors that could affect the results of the modification are practically identical. However, nitriding in a glow discharge with a constant current supply does not ensure the treatment of the inner surface uniformly throughout the entire depth, and with significant ratios of length to diameter (more than 4), the inner surface of the hole remote from the ends is practically not nitrided. Therefore, a process technology and a device for quality control of anhydrous nitriding in glow discharge (BATR) of long holes with cyclically switched power supply of the gas discharge chamber have been developed.
Establishing the regularity of wear of a cylindrical brush of the mounted sweeping equipment of a garbage truck depending on its rotation frequency
(Хмельницький національний університет, 2024) Bereziuk, O.V.; Savulyak, V. I.; Kharzhevskyi, V. O.; Semichasnova, N. S.; Harbuz, E. S.
The article is dedicated to establishing the regularity of wear of a cylindrical brush of the mounted sweeping equipment of a garbage truck depending on its rotation frequency. Using the mathematical dependencies and corresponding regression analysis programs, it was established a power law of change in the wear of the cylindrical brush of the garbage truck's mounted sweeping equipment on the frequency of its rotation, which can be used to build a mathematical model of the hydraulic drive of the improved mounted sweeping equipment of a garbage truck, taking into account the wear of its working bodies. A graphical dependence of the change in the wear of the cylindrical brush of the garbage truck's mounted sweeping equipment on its rotation frequency was plotted, which confirmed the sufficient convergence of the obtained regularity. The graph of the influence of the rotation frequency of the cylindrical brush of the garbage truck's mounted sweeping equipment on its wear demonstrates the expediency of its reduction. It has been established that for a Ukrainian-made sweeping machine of the serial model KO-713-01, which is equipped with a cylindrical brush with a rotation speed of 3200 rpm, its wear according to the obtained regularity will reach 86.5 mm. It was found that reducing the rotational speed of the cylindrical brush of the garbage truck's mounted sweeping equipment from 62 sec-1 (3700 rpm) to 26...38 sec-1 (1550...2250 rpm) leads to a decrease in its wear by 2 orders of magnitude. The expediency of conducting additional research to identify further ways to improve the wear resistance of the cylindrical brush of the garbage truck's mounted sweeping equipment has been established.
Analysis of tribological aspects during operation and repair of internal combustion engine valve mechanism parts
(Хмельницький національний університет, 2024) Vychavka, A.A.; Dykha, O.V.; Hetman, M.V.
The problem of researching mechanisms of wear of valve mechanism parts remains very relevant due to the need for constant improvement of the design and increase in durability of internal combustion engines. The paper provides an overview of modern research on the following issues: analysis of operating conditions and malfunctions of the valve mechanism of the internal combustion engine, research on friction and wear of valve mechanism parts, repair and restoration technologies, increasing the wear resistance of engine valves, modeling, calculations of valve mechanism parts. It is shown that an important aspect for the analysis of the wear resistance of valve mechanism parts is the operating conditions and the nature of damage to the surfaces of the friction pair parts. The existing hypotheses about the mechanisms of friction, lubrication and wear of valve mechanism parts are considered, the designs of test stands are given, and the results of tribological tests are analyzed. It is substantiated that the technological methods of surface engineering are becoming an increasingly viable alternative to structural changes to improve the performance of valve mechanism parts. An overview of calculation methods for assessing the stress and thermal state of valve mechanism parts of internal combustion engines is provided.
Restoration and wear resistance of electric transport sliding contacts
(Хмельницький національний університет, 2024) Kovtun, O. S.; Dytyniuk, V. O.; Staryi, A. L.; Fasolia, V. O.
The electrical contact insert of the current-carrying suspension of the electric vehicle belongs to the fastwearing elements that require frequent replacement and attention to ensure standard performance. The purpose of this study was to develop a technology for manufacturing graphite-filled electrical contact inserts from waste materials and by modifying the composition of the composite. As a result of difficult operating conditions, coal current collector inserts of electric transport are subject to considerable wear. The causes of increased wear are electrocorrosion in contact with the conductor under current, abrasive wear from sliding on the wire with increased dustiness and air humidity. The technological process of manufacturing graphite current-collecting inserts from used graphite components is proposed. To prove the functionality of the restored current-collecting inserts, the strength, electrical conductivity and tribological characteristics of the material were tested. The results of experimental tests showed a slight decrease in material hardness and an increase in electrical resistance within acceptable limits. Bench wear tests showed improved tribological properties of the restorative insert material with the addition of copper powder.
Tribotechnical coatings
(Хмельницький національний університет, 2024) Zemlyanoy, A.O.; Bys, S.S.; Shchepetov, V.V.; Kharchenko, S.D.; Kharhenko, O.V.
Wear and tear limits the possibilities and shortens the operational life of modern technical systems. Therefore, the importance and necessity of consideration of issues aimed at reducing frictional forces and increasing wear resistance cannot be doubted. The paper summarizes the theoretical and applied results of triboresistance studies of detonation coatings of the Nb-Zr-V-Si-C-MgC2 system under conditions of constant loading in the field of sliding velocities. It has been established that the ratio of the quality of the components that make up the surface modified structures changes. It is noted that at the initial test speeds the presence of lower metal carbides that are part of the coating dominates, with an increase in speed under the current load due to solidphase and diffusion processes, higher ones are formed in the graphite matrix carbides with enhanced thermodynamic properties
Experimental installation for wear tests of materials and coatings
(Хмельницький національний університет, 2024) Stechyshyn, M.; Dykha, O.; Oleksandrenko, V.; Tsepenyuk, M.; Kurskoi, V.; Oleksandrenko, Ye.
On the basis of the analysis of existing tribological testing methodologies, which includes the selection of controlled wear parameters, the influence of the type of friction, contact geometry, surface roughness, the scheme of tribological research, the choice of a machine 2168UМТ for friction testing of materials is substantiated. The friction machine allows you to install three samples at the same time, change the pressure in the contact zone in a wide range, control the moment of friction, the rotation frequency of the counterbody, the number of revolutions (friction path), change the rotation frequency, respectively, the sliding speed, automatically limit the distance traveled and other functions. The method of wear is adopted according to the finger-ring scheme, linear wear is monitored using an indicator rack with a value of divisions of the measuring device of 0.001 mm. To fix the samples on the machine caliper, holders were designed and manufactured, which ensure the self-fixation of the sample on the counterbody - a spherical joint made of the rolling body of the bearing. due to the fact that the samples were pressed against the counterbody with a force corresponding to the nominal contact pressure, they were self-aligned. After the sample was self-assembled, the whole structure was fixed by tightening the nuts. The counterbody is made of a rolling bearing ring, the material is steel SHX15, the hardness of the base is HRC 61. Three devices are mounted on the caliper for permanent lubrication of the running track immediately before the approaching sample. Thus, at certain values of pressure and speed, the mode of marginal friction can be reached, which was marked by a low coefficient of friction.
Optimization of technological parameters at discrete strengthening of steel cylindrical surfaces
(Хмельницький національний університет, 2024) Dykha, O.; Dytyniuk, V.; Hrypynska, N.; Vychavka, A.
The technologies of continuous strengthening of technological surfaces have practically exhausted their capabilities, which calls for the creation of fundamentally new approaches. The application of the principles of discrete-oriented strengthening of tribosystems has wide prospects for improving existing methods of strengthening due to the selection of modes and control of the geometric structure of the surface layer. The essence of the discrete-oriented strengthening method is the application of combined electromechanical processing and electrocontact cementation of cylindrical surfaces. The purpose of the work is to determine the parameters of discrete processing of cylindrical steel parts that are optimal according to the surface hardness criterion. Using the Statistica program, a factorial experiment was implemented according to the Box-Behnken plan, and the results of dispersion and regression analysis of the influence of processing parameters on microhardness were obtained. It was established that the following optimal parameters of DOZ processing are necessary to achieve the maximum values of microhardness (5950 MPa): current strength-500A, force-350 N, contact time-0.3 s.
Determination of the regularity of the rate of wear of the working hydraulic cylinder of the mechanism of the sealing plate of the garbage truck from the pressing force
(Хмельницький національний університет621, 2024) Bereziuk, O.V.; Savulyak, V.I.; Kharzhevskyi, V.O.; Alekseiev, A.Ye.
The article is dedicated to the study of the influence of the pressing force on the wear resistance of the working hydraulic cylinder of the mechanism of the sealing plate of the garbage truck. The usage of a mathematical dependencies and appropriate software programs for regression analysis made it possible to determine the exponential regularity of the change in the rate of wear of the working hydraulic cylinder of the mechanism of the sealing plate of the garbage truck depending on the pressing force. A graphical dependence of the change in the rate of wear of the working hydraulic cylinder of the mechanism of the compacting plate of the garbage truck on the pressing force was made up, which confirmed the sufficient convergence of the obtained regularity. Graph of the influence of pressing force on wear rate of working hydraulic cylinder of the mechanism of the compacting plate of the garbage truck demonstrates the expediency of its increase. It was established that for the garbage truck of Ukrainian production of serial model KO-436, the rate of wear of the working hydraulic cylinder of the mechanism of the sealing plate of the garbage truck according to the obtained regularity will be 0.257 μm/h. The expediency of conducting additional studies to determine further ways to increase the wear resistance of the working hydraulic cylinder of the sealing plate mechanism of the garbage truck has been established.
Modeling surface structure of tribotechnical materials
(Хмельницький національний університет, 2024) Drach, I.; Dykha, M.; Babak, O.; Kovtun, O.
Modern tribology makes it possible to correctly calculate, diagnose, predict and select appropriate materials for friction pairs, to determine the optimal mode of operation of the tribo-joint. The main parameter for solving friction problems and other problems of tribology is the topography of the surface. The main purpose of the models in these tasks is to display the tribological properties of engineering surfaces. In the framework of the classical approach, the topography of the surface is studied on the basis of its images from the point of view of functional and statistical characteristics: the evaluation of the functional characteristics is based on the maximum roughness along the height and the average roughness along the center line, and the statistical characteristics are estimated using the power spectrum or the autocorrelation function. However, these characteristics are not only surface properties. They depend on the resolution of the device for measuring the surface geometry and the length of the scan. However, the degree of complexity of a surface shape can be represented by a parameter called the fractal dimension: a higher degree of complexity has a larger value of this parameter. Fractal dimensionality is a characteristic of surface relief and makes it possible to explain tribological phenomena without the influence of resolution. This article provides an overview of mathematical approaches to the description of the relief of engineering surfaces, in particular statistical, stochastic and topological modeling, their limitations, advantages and disadvantages. The implementation of the principles of the theory of fractal structures is discussed, which makes it possible to introduce the degree of imbalance of the tribological system into the analysis of structure formation in the surface and near-surface layers of materials and to describe the development of friction and wear processes. This is the basis for controlling the structure of the surface layers of materials with given properties. The concept of fractals, used for the quantitative description of the dissipative structure of the tribojunction zone, makes it possible to establish a connection between its fractal dimension and mechanical properties, as well as critical states of deformation of metals and alloys. The course of research and stages of fractal modeling, the classification of methods of fractal analysis of the structure of engineering contact surfaces are considered. A critical analysis of modern models based on the energy-spectral density function, which are quite similar to fractal models, is presented. Readers are expected to gain an overview of research developments in existing modeling methods and directions for future research in the field of tribology.

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