Ukrainian Journal of Mechanical Engineering and Materials Science. – 2023. – Vol. 9, No. 2

Permanent URI for this collectionhttps://ena.lpnu.ua/handle/ntb/61139

Науковий журнал

Засновник і видавець Національний університет «Львівська політехніка». Виходить двічі на рік з 2015 року.

Ukrainian Journal of Mechanical Engineering and Materials Science = Український журнал із машинобудування і матеріалознавства : науковий журнал / Lviv Politechnic National University ; editor-in-chief Oleksiy Lanets . – Lviv : Lviv Politechnic Publishing House, 2023. – Volume 9, number 2. – 94 p.

Український журнал із машинобудування і матеріалознавства

Зміст (том 9, № 2)


1
12
26
36
45
57
66
75
83
91

Content (Vol. 9, No 2)


1
12
26
36
45
57
66
75
83
91

Browse

Search Results

Now showing 1 - 10 of 10
  • Thumbnail Image
    Item
    The dependence of thermal processes in non-metallic heterogeneous materials on mechanical vibration loads
    (Видавництво Львівської політехніки, 2023-02-28) Tonkonogyi, Volodymyr; Holofieieva, Maryna; Levynskyi, Oleksandr; Klimov, Sergii; Dasic, Predrag; Odesa Polytechnic National University; Academy of Professional Studies Sumadija
    One of the promising directions in the development of mechanical engineering is using of new non-metallic heterogeneous materials with high physical and mechanical properties. Such materials consist of two or more components (reinforcing filler and polymer matrix) and have specific physical and mechanical properties that are different from the properties of the constituent components. This is achieved by forming a complex developed structure. Reliable control methods play an important role in ensuring the quality of such structures. The paper considers an acoustic infrared thermometric method of control, which is based on the interaction of structural defects with acoustic waves. At the same time, thermal energy is generated at their boundaries, which is an indicator not only of the presence of cracks but also of their direction and development. a mathematical model has been developed that describes the transformation of the energy of mechanical vibrations into thermal energy, which occurs in non-metallic heterogeneous materials.
  • Thumbnail Image
    Item
    Study of durability in the connection “cone-tungsten carbide insert” for tension dependence
    (Видавництво Львівської політехніки, 2023-02-28) Slipchuk, Andrii; Jakym, Roman; Bembenek, Michal; Lviv Polytechnic National University; Drohobych State Pedagogical University by name I. Franko; AGH University of Science and Technology in Kraków
    During and after the technological operation of pressing these factors significantly determine the residual stress states of tungsten carbide inserts, as well as in the areas near the holes of the cones’ crowns of the cone. The stressed state of the inserts and the magnitude of the stress concentration determine their fatigue strength of them and the durability of the inserted carbide rockblasting equipment of the cones in the area where the inserts the cone. Dimensional analysis was done for the inserts and holes in the cones of bit and it was established that size errors of component links of dimensional chains are distributed according to laws that are similar to the normal law of distribution of random variables. The test was carried out according to the criteria of Pearson and Kolmogorov. The influence of various random and systematic factors results to the dispersion of dimensions on the dimensional processing of conjugated surfaces. The amount of tension is a function of the dimensions for mating surfaces during assembly operations. Dispersion of dimensions for the component links of the dimensional chain of a press connection causes the formation of a practical field of dispersion of the closing link. Accuracy control for the closing link in the dimensional chain is impossible if there are no direct measurements of the constituent links. A mathematical model of the process of assembling “cone-tungsten carbide insert” joints was created. For this, the methods of mathematical statistics were applied in the study. It was established that the tension values have a greater influence on the force of pressing inserts into the holes of drill steels 14 NiCrMo1, when its hardness value is HRC 59–60 compared to HRC 48-50. This dependence has a linear character within the limits of the studied tension values. The established relationships make it possible to reasonably and most accurately form selective groups of inserts and mark holes for them. This method significantly reduces losses in the production of drilling tools.
  • Thumbnail Image
    Item
    Analysis of the drive of electric vehicles with its different configurations
    (Видавництво Львівської політехніки, 2023-02-28) Myskiv, Teodozii; Lviv Polytechnic National University
    In the process of car development, its drive is continuously improved. The properties of different types of driving with an internal combustion engine (ICE) are well-studied [1]. ICE's bleak future has forced major automotive manufacturers to turn to electric mobility. The motor, integrated with final drive and differential, is compact and takes up little axle space, making it easier to assemble the drive into one axle or all-wheel drive. Electric vehicles have many advantages over vehicles with ICE: no emissions, high efficiency, quiet and smooth operation, braking energy recovery, simplified maintenance, etc. The functional and fundamental principles of electric vehicles and vehicles with ICE are similar, but there are some features. The characteristic of the electric motor (hereinafter referred to as the motor) is ideal for the drive – it has a large zone of constant maximum power, and the maximumtorque appears immediately during starting. The motor, integrated with final drive and differential, is compact and takes up little axle space, making it easier to assemble the drive into one axle or all-wheel drive. Possible drive designs without a differential with two motors and two final drives on the axle, or with low-speed motors without final drives. The heavy battery is placed in the floor, so the stability of the electric car is high. The maximum possible recovery of braking energy is added to all the positive properties of allwheel drive in the case of an electric car. To reduce the power consumption in the drive, two motors provide a drive mode with only one motor. Among electric vehicles with one-axle drive, front-wheel drive prevails due to using multienergetic front-wheel drive platforms, stable stability and handling performance and good traction properties in winter conditions. The advantage of rear-wheel drive is the ability to realize greater traction forces during acceleration or movement on the rise due to the dynamic redistribution of the load on the rear axle. However, during braking, due to the dynamic redistribution of the load on the front axle, the possibility of recuperation of braking energy decreases. For amore detailed analysis of the drive, typical electric vehicles are selected, the characteristics of their drive motors are given, traction characteristics are calculated and constructed in the traction force coordinates – speed of movement, the realized adhesion coefficients are determined, and appropriate conclusions have been drawn.
  • Thumbnail Image
    Item
    Analysis of the influence of the displacement of the gear rack profile of the pair evolution gearing on the quality indicators of the transmission
    (Видавництво Львівської політехніки, 2023-02-28) Protasov, Roman; Magdolen, Ľuboš; Danko, Jan; Lanets, Olena; Vorontsov, Borys; Slovak University of Technology in Bratislava; Lviv Polytechnic National University; National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”
    The article is devoted to the study of the influence of the modification of the paired evolute gearing with convex-concave contact on the quality indicators of transmission, namely, the contact pressure and the speed of slippage in the engagement. Previous studies of evolute gears showed the presence of characteristic zones on the side surface of the tooth, which have worse values of quality indicators than in similar involute gear. One of the ways to remove these zones or to reduce their impact on the load capacity of the transmission is to modify the tooth profile, which will be implemented by shifting the profile of the processing gear rack. A displacement factor is added to the equation of the rail profile curve, which has the same value for the gear and wheel teeth, but the opposite sign. On the basis of the developed equation, the side profiles of the teeth of the gear and the wheel were constructed. Several values of the rack displacement coefficient with a positive and negative sign for the gear teeth are considered. The results of the research allow us to evaluate the influence of the amount and direction of the rail displacement on the curvature of the tooth profiles, the contact pressure in engagement along the height of the tooth, and the relative and absolute speed of sliding. Themodifications of the profile of the processing toothed rack proposed in thisworkwill expand the existence of paired evolute gears with a different set of quality indicators. This will make it possible to design gears with rational values of contact pressures and slip speeds when they are used in heavily loaded transmissions created for specific operating conditions. Gears with relatively high slip speeds can be used in road and construction equipment transmissions, which are characterized by lowshaft rotation frequency, in which the speed of slip between the teeth does not have a significant effect on the life or efficiency of the transmission. Otherwise, gears with relatively low slip speeds are very relevant when they are implemented in the transmission of modern and promising vehicles with a hybrid or fully electric power unit, especially in the case of passenger cars with high-speed electric motors.
  • Thumbnail Image
    Item
    Selection of a rational method for hardening carbide cutting tools for heavy engineering
    (Видавництво Львівської політехніки, 2023-02-28) Kovalev, Viktor; Klymenko, Galyna; Vasylchenko, Yana; Shapovalov, Maksym; Manokhin, Andrey; Donbass State Engineering Academy; V. Bakul Institute for Superhard Materials NAS of Ukraine
    An important task is to improve cutting tools for high-precision productive machining of difficult-to-machine materials by applying the latest tool hardening methods. This is especially true for carbide-cutting tools. The paper analyzes the current state of the problem of improving the tooling of new machine tools for high-precision productive machining of hard-tomachine materials. The main known methods of increasing the wear resistance and strength of carbide tools can be divided into the following groups: structural methods; mechanical hardening; wearresistant coatings; chemical and thermal treatment; laser hardening; plasma-arc hardening; radiation hardening; ionic alloying; magnetic abrasive treatment; and pulsed magnetic field treatment. The choice of a particular hardening method depends on many factors that determine its effectiveness and costs in certain production conditions. The conditions for machining large-sized parts at heavy engineering enterprises are analyzed. It was found that, along with wear, the destruction of the cutting part in the form of pitting and fracture is significant. Statistical studies have proven that when machining on heavy machine tools, the cutting force allowed by the machine tool mechanisms does not limit the cutting modes. The maximumvalues of forces are up to 10 times higher than their average value, which is usually used to calculate the design parameters of cutting tools An analysis of various methods for improving the physical and mechanical properties of carbide tool materials has shown that the best combination of cost and production efficiency is observed in pulsed magnetic field treatment. The use of magnetic fields in cutting processes and tool hardening is a promising area of high-technology development in machining. Increasing tool life can be achieved by the influence of a magnetic field either on the conditions of the cutting process or on the structure and physical and mechanical properties of tool materials with ferromagnetic components.
  • Thumbnail Image
    Item
    Construction of a mathematical model of an unbalanced vibrating separator on a spring suspension
    (Видавництво Львівської політехніки, 2023-02-28) Topilnytskyy, Volodymyr; Vyshatytskyy, Volodymyr; Lviv Polytechnic National University
    In the article, a mathematical model of the oscillating motion of a vibrating separator is constructed. The methods of nonlinear mechanics and the calculation scheme of the vibration separator with an eccentric and a spring suspension, which is presented in the form of a flat mechanical system with four degrees of freedom, were used for its construction. The amplitude of oscillations of the vibration separator capacities in the vertical plane is greater than the amplitude of its oscillations in the horizontal plane. It is believed that the containers of the vibroseparator move only in the vertical plane, that is, they are in planar motion. The obtained mathematical model makes it possible to investigate the influence of the separator parameters with their arbitrary combination on the productivity of its work with the aim of its optimization.
  • Thumbnail Image
    Item
    Increasing of vibratory conveying velocity by optimizing the normal vibration
    (Видавництво Львівської політехніки, 2023-02-28) Vrublevskyi, Ihor; Hetman Petro Sahaidachnyi National Army Academy
    The paper is dedicated to researching the influence of normal vibration on the vibratory conveying velocity of particles on an inclined track that performs independent longitudinal and normal oscillations (two-component vibration). The study considers the optimizing conditions of the conveying velocity for different laws of oscillating components (harmonic, polyharmonic, oscillations with piecewise constant acceleration) with a limited value of the longitudinal acceleration of conveying track and with maximal normal acceleration that does not exceed the gravitational acceleration (non-hopping modes of moving, when particles slide without detachment from the surface). The optimization criterion is the maximal distance, traveled by the particle during the oscillation period, or the maximal value of dimensionless conveying velocity, depending on several dimensionless parameters. The maximal conveying velocity with polyharmonic normal oscillations is achieved at a certain ratio of the amplitudes of harmonic oscillation, which essentially depends on the track’s inclination angle to the horizon. The ratios of the amplitudes of harmonic oscillation, which practically do not reduce conveying velocity at any inclination angles, are proposed. Two-component vibratory conveying under normal oscillations with piecewise constant acceleration is considered in optimal non-hopping modes of a particle moving with one forward (or upward on an inclined track) sliding stage and one backward (or downward) sliding stage during the oscillation period. The equations for determining the dimensionless conveying velocity are derived for different values of dimensionless parameters, such as the inclination angle parameter (a ratio of an inclination angle tangent to a frictional coefficient) and the intensive vibration parameter (a ratio of the amplitudes of longitudinal and normal oscillations, divided by the frictional coefficient). The effectivity of polyharmonic normal oscillations in two-component vibratory conveying is compared with the effectivity of normal oscillations with piecewise constant acceleration. Maximal conveying velocity is achieved at certain values of phase difference angles between longitudinal and normal oscillations, which are called optimal. The value of dimensionless conveying velocity V increases with the increase of asymmetry of normal oscillations, which is described by the ratio n of the maximal acceleration of the track when moving down to the acceleration of gravity. This ratio n corresponds to the number of harmonics for polyharmonic oscillations. A comparison of values of V for normal oscillations with piecewise constant acceleration shows an advantage in velocity compared to polyharmonic normal oscillations at the same number n of harmonics, especially with increasing inclination angles. The research was carried out by the numerical step-by-step integration method, which allows for performing calculations with any given accuracy. The obtained results are demonstrated in figures and comparative tables.
  • Thumbnail Image
    Item
    Contents
    (Видавництво Львівської політехніки, 2023-02-28)
  • Thumbnail Image
    Item
    Comparative characteristics and selection of speed bearings
    (Видавництво Львівської політехніки, 2023-02-28) Vishtak, Inna; Savulyak, Valeriy; Vinnytsia National Technical University
    The characteristics of bearing supports have been considered. Improving the efficiency of mechanical processing, the quality of operation of mechanisms that use sliding bearing supports, and ensuring stable operation are always important tasks. Solving these tasks contributes to reducing labor costs, reducing operating costs, and increasing the productivity of individual operations. The following main criteria are proposed for the selection of supports: the magnitude of the loads that supports can withstand; the range of allowable shaft rotation frequencies; accuracy in maintaining the position of the axis of shaft rotation; stability of shaft rotation (possibility of autooscillations and undesirable transient processes); energy costs and economic indicators of manufacturing and operation; vibroacoustic characteristics (noise level, sound level). The study of the movement of the working body that separates the friction pairs in the bearing is based on two fundamental laws of hydrodynamic lubrication theory: the law of mass conservation and the law ofmomentumconservation.Mathematicalmodels of supports with fluid lubrication, based on the Navier-Stokes equations, were used. The requirements for bearing supports are formulated on the basis of the tasks solved by the entire mechanism. The flow parameters of the working body affect the load-bearing capacity of radial bearings, and the proposed evaluation dependencies can also be used for tapered supports. The calculation results indicate a significant influence of the flow parameters of the working body on the expansion of the areas of rarefaction and the range of their values, as well as on the reduction of the area and range of increased pressures. It has been established that with small shaft eccentricities rotating at speeds of 60–70 m/s and with a radial clearance of 80 μm, the increase in load capacity can reach 20 %. An important qualitative feature has been identified: with an increase in the Reynolds number Re*, the load capacity of the bearing increases. The greatest intensity of changes in load capacity due to the influence of flow parameters of the working body is observed at a relative eccentricity of e = 0.2–0.4. The terms in the Navier-Stokes equation that take into account the parameters of the working fluid flow can have values that are comparable to other terms, so ignoring them is not always permissible.
  • Thumbnail Image
    Item
    Technological features of restoration of rims of support rollers for tracked vehicles
    (Видавництво Львівської політехніки, 2023-02-28) Dzyubyk, Andrij; Dzyubyk, Liudmyla; Zinko, Yaroslav; Dzhaliuk, Oleh; Lviv Polytechnic National University
    The use of tracked (caterpillar) vehicles enables us to meet the requirements concerning harmless impact upon the environment, the considerable amounts of work to be fulfilled being saved. In particular, as compared to wheeled vehicles, there is less pressure upon the ground; there is also the opportunity to work in specific conditions of marshy, sandy, and low-bearing soils; stable performance in hard climatic conditions, etc. is also possible there. A necessary and important part of the tracked vehicle is its special suspension. Such a suspension contributes to smoother motion of the mechanism, it also cushions shocks, and ensures transmission of motion from the engine to the tracks. Independently of the design of the suspension, there are always several couples of support rollers. These rollers make up the intermediate link between the mover and the carrier frame, they transmit not only great weight but also the created loading, they guide the tractor’s caterpillars, etc. In the course of their work, the support rollers of tracked vehicles experience intensive wear and tear of the outer surface of their rims. As a result, changing them is necessary; dismounted ones are to be repaired. The use of restorative technology through overlaying (building up) by means of the electric arc is considered in this paper. This enables us to ensure cost savings and to repair support rollers of hardly loaded track vehicles. It is also possible to increase their serviceability by optimizing the overlayed metal; in particular, by increasing the hardness of the overlayed layer and increasing its resistance against impact and abrasive wear. The weldability of the main metal of a support roller has been analyzed. It is shown that the use of high-carbon material complicates the conditions for overlaying the outer rim. It is necessary to use pre-heating to high temperatures. This reduces the tendency of the material to form hardening structures and cracks after the overlaying. Investigations of peculiarities of overlaying a cylindrical surface of the rim of a tractor’s roller have been conducted. In particular, the limit values of the length of a weld pool depending on the diameter (value of wear) of the overlayed rim of a roller have been determined. It is shown that it is necessary to carry out the displacement of the arc from the zenith. This ensures the necessary formation of the weld-pool and the absence of spreading of the metal overlayed on the rim. The determination of the value of heat input of overlaying a roller has been carried out, the heat input is considered as a function of parameters of the electrode wire. Verification calculation of the obtained values of specific power for the permissible length of the weld-pool has been conducted. Concretization of the obtained results was carried out by taking into account the optimal range and permissible rate of cooling in overlaying the main material of a support roller. According to special nomograms, the dependence between the rate of cooling and the heat input of overlaying has been established. Especially, there were investigated the temperature conditions during overlaying the weld beads. It is shown that heating the roller takes place at the expense of neighboring weld beads. It is established that in overlaying at the determined values of heat input (per unit length) there can be achieved the temperature of auto heating is sufficient for the pre-heating of a roller.