Ukrainian Journal of Mechanical Engineering and Materials Science

Permanent URI for this communityhttps://ena.lpnu.ua/handle/ntb/31565

Browse

Now showing 1 - 20 of 183

Electromechanical model of machine for vibroabrasive treatment of machine parts
(Publishing House of Lviv Polytechnic National University, 2015) Gorbatiyk, Ruslan; Palamarchuk, Igor; Chubyk, Roman
A lot of operations on trimming clean and finishing – stripping up treatment, first of all, removing of burrs, rounding and processing of borders, until recently time was carried out by hand, and hardly exposed to automation and became a serious obstacle in subsequent growth of the labor productivity. Machines with free kinematics connection between a tool and the treating parts is provided by the printing-down of all of the surface of the machine parts, that allows us to effectively treat both internal and external surfaces of the machine parts. The analysis of literary sources, patents and charts of methods of the intensification of the processes of vibro abrasive treatment, allowed us to determine the basic directions of development of vibro machines constructions for intensification of the trimming - stripping of the machine parts in a freely granular environment in default of hard kinematic connection between the parts and the tool. The feature of vibro abrasive treatment is a free kinematic connection between a tool and the machine parts, i.e. there exists complication in providing with the stable beforehand set technologically optimum influence of abrasive grains on treated parts under variable parameters of the working chamber of vibroabrasive machine. The purpose of this work is the development of a structural electromechanical model of a vibromachine for adaptive vibroabrasive treatment of the machine parts. To solve this problem, the structural electromechanical model of vibromachine for adaptive vibroabrasive treatment of machine parts was developed. The offered machine is able to provide minimum energy consumption on the vibrodrive of vibroabrasive machine due to providing and maintenance of the permanent resonance mode of operations of working chamber.
Determination of porosity of materials by means of metallographic method swith a help of application programs
(Publishing House of Lviv Polytechnic National University, 2015) Huliieva, Nataliia
Theoretical and experimental investigations of porous permeable materials of saponite-titanium and saponite-aluminium composites are presented in this work. their qualitative and quantitative indexes are determined in PhotoM and Smart-eye applied programs. Metallographic images are presented by combination of structural components with different proportions: phases, shape and color, grain boundaries. The limits of technological parameters and synthesis of porous permeable materials on the basis of saponite-titanium and saponite-aluminium composites with the necessary balance of the designed and functional indexes and their variation with changes in individual properties have been studied. On the basis of results of the investigations, regimes of shaping of saponite-titanium and saponite-aluminium composites are stated and substantiated. Dry radial-isostatic compaction and self-propagating high-temperature synthesis are applied. The porosity for these composites is determined. Recommendations on application of porous permeable materials are developed; and the branch of their application is determined: filtering porous permeable materials of saponite-titanium ensure the necessary purification and tertiary treatment of water for drink preserving their main natural characteristics: balance of chemical composition, organoleptic indexes, safety, physiological full value, and biological stability; and the filtering porous permeable materials of saponitealuminium composite ensure treatment of sewage, of service and process waters. The suggested and tested resource-saving technology has been introduced in enterprises of the municipal services “Lutsk Vodokanal” and PAT “SKF-Ukraina” of Lutsk city; this technology provides manufacture of saponite-titanium composites for purification of water for drinking and saponite-aluminium composites for treatment of sewage and service and process waters; and developed, manufactured and tested porous permeable materials satisfy the requirements of state in the field of water supply, as well as in the food and industrial sectors, that, in its turn, plays an important role in solving complicated problems of modern materials science.
The structure, mechanical and electrophysical properties of monocrystalline silicon under influence of constant magnetic field
(Publishing House of Lviv Polytechnic National University, 2015) Kutzova, Valentina; Nosko, Olha; Sulay, Andrey
The monocrystalline silicon is one of the most important materials in the view of the fact that it is used in contemporary electronics. The issues concerning silicon processing methods up to now attract a lot of attention of scientists all around the world. From this point of view, the influence of constant magnetic field upon the monocrystalline Czochralski silicon had been studied. The processing of monocrystalline Cz-Si (alloyed with Zr, Hf, Mg, Al, and unalloyed) in weak constant magnetic field (0.07 Tesla) has been carried out. The influence of weak constant magnetic field on the structure, mechanical and electrophysical properties of silicon, namely, increasing of internal defects density, forming of polycrystalline structure in unalloyed silicon, significant increment of microhardness and considerable degradation of minority carriers time of life has been noted. The qualitative explanations of magneto-stimulated phenomena in studied specimens from the viewpoint of spin-conversion as well as changes of electronic states density in the space-time as well as that of the influence of alloying elements on the critical points of first type phase transitions in silicon have been suggested. It has been found that using the weak constant magnetic field lets us to manage the properties of silicon by acceleration or slowing the shear and shear-diffusion phase transitions.
The hydro-automatic damping system against dynamic vibrations
(Publishing House of Lviv Polytechnic National University, 2015) Pelevin, Leonid; Karpenko, Mykola; Lavryk, Stanislav
A review and analysis of the developed hydraulic system for quenching dynamic oscillations has been carried out. A mathematical model for determining the operation delay time of the hydraulic system of the dynamic quenching of oscillations has been created. A period’s calculation of cleavage of the soil and the operation delay time of quencher dynamic oscillations from which it is possible in theory to establish the ability of the hydraulic system of dynamic quenching of oscillations to operate in due time is performed. A hydraulic system of dynamic quenching of oscillations that occur inside the working unit to prevent the transmission of vibrations to the base of the machine is developed. The analysis of the damper’s means and the method of dynamic damping was conducted, based on which hydraulic system for dynamic quenching of oscillations has been developed. A mathematical sequence for determination of the operation delay time of the quencher was created. The parameters allow us to construct experimental model of hydraulic system for dynamic quenching of oscillations. The basic idea is the presence of feedback from the hydraulic system in the form of reed switch, which allows us in due time to turn on a pump and supply additional portion of hydraulic fluid for more efficient operation of the quencher. A hydraulic damping system which allows full vibroisolation is developed. At the expense of that, the average speed of operation is between 10–20 % of the period of soil cleavage.
Identifying the elastic moduli of composite plates by using high-order theories
(Publishing House of Lviv Polytechnic National University, 2015) Diveyev, Bohdan
The study aims to predict elastic and damping properties of composite laminated plates from the measured mechanical characteristics. The elastic constants and damping properties of a laminated element are determined by using experimental data and the results of a multi level theoretical approach. Solution examples for particular problems are given. On the basis of static three-point bending tests, measured eigenfrequencies, and refined calculation schemes, the elastic properties of layered composite beams were identified. For determining Young’s and shear moduli, the method of genetic minimization of error function was used. It is shown that, by employing combined criteria, the transverse elastic moduli can be determined uniquely. It is shown that, by employing combined criteria, the transverse elastic moduli can be determined. The elastic modules were also determined from measured vibration eigen-frequencies of the beams. New combined criteria of identification – schemes averaged over the calculation results for a homogeneous beam and for a sandwich with a core identical to the homogeneous beam and rigid outer layers are considered. The error function is chosen as the sum of error functions for the homogeneous beam, and for the sandwich. In the present study, combined identification schemes making it possible to unequivocally determine the transverse modules and Poisson ratio are suggested.
Cutter force and influence of elastic deformation of technological system of gear-hobbing machine on precision of radial-circumferential method of gear cutting
(Publishing House of Lviv Polytechnic National University, 2015) Hromniuk, Serhii; Hrytsai, Ihor
The relevance of the problem which is solved in this article has been substantiated. In modern machines and equipment, rotary motions which cannot be implemented without gear wheels and gear trains are always present. Attainment of high performance of a machine – increase in loading with simultaneous increase in speed, increase in transmitted forces and moments, decrease in noise during operation, ensuring high indexes of failure-free performance and longevity of a machine – depends on precision in manufacturing the gear wheels and gear trains. These requirements to modern machines are put simultaneously with improvement of technology of their manufacturing and with creation of new effective methods of machine parts working. A new effective method of radial-circumferential (RC) gear cutting by disk-type cutting tool under the conditions of continuous generation (revolving) around is described; this way enables us to considerably reduce the expenditures for expensive and complicated cutting tools, to increase productivity of the process, and to increase precision of gear wheels. However, for application of this method in the course manufacturing, it is necessary to develop a technique of prediction of the precision of the gear cutting; such a technique being able to serve as a basis of substantiation of the choice of regimes of gear cutting. Principles of the mathematical model of cutting force of gear cutting, i.e. a model which is based on modelling of parameters of shearings made by a disk-type milling cutter, are presented in this article. This mathematical relation takes into account the intensity of deformation of the layer which is being removed and the strength of the material which is being machined; the model also enables us to determine the force on individual blades and its total value on all the active teeth in RC-method at any instant of time of milling as a function of the turn angle of the cutting tool. Analysis of cutting force has indicated that in one revolution of a milling cutter the cutting force varies according to aperiodic regularity, and its peak values are considerably less than the force of gear-tooth milling by a hobbing cutter under the same initial conditions. Since the disc-type gear milling cutter, as compared with the hobbing cutter, is considerably more sensitive to elastic deformations, the cutting force can essentially influence the error of gear cutting of ring gears. Proceedings from this, the influence of primary errors and that of elastic deformations which are caused by variable cutting force in the cycle of revolution of the milling cutter and formation of gears on the error of the working is investigated. Laws of the influence of radial, axial, and torque deformations of the elastic system of a machine on the deviations of parameters of the teeth from their rated ones and on the error of profiles in the process of gear milling according to radial-circumferential method are presented. The enhance of precision of tooth cutting and reduction of the total error becomes possible due to the choice of such regimes of cutting (first of all, axial feed) under which the necessary precision of the chosen parameter of precision, in particular, profile error, can be attained.
Propagation of elastic-tough-plastic wave in a rod of ideally plastic materialwhich possesses the property of yield delay
(Publishing House of Lviv Polytechnic National University, 2015) Andrusyk, Yaroslav
The great number of theoretical and experimental investigations indicate that it is necessary to consider plastic deformation of metals as a process which proceeds in certain time interval. However, in such approaches, contradictive points of view emerge concerning investigation of wave processes in materials which possess peculiar properties. In order to describe different mechanical effects, new models of plastic medium are being improved. The phenomenon of emergence of a tooth yield in the strain diagram belongs to such properties of materials. In this article, investigation of propagation of elastic-tough-plastic wave is conducted in a semi-infinite rod; it is conducted on the basis of the electromechanical model of ideal elastic-plastic material with yield delay. The dynamic criterion of plasticity, which is stated by the author is used here. The solving of the problem is conducted according to the statement where constant force is abruptly exerted on a bult of an unloaded rod. the main solution is obtained in stresses, both for elastic and plastic domains of the rod. It is established that characteristic curves which separate an elastic domain from a plastic one and vice versa are frontal lines of weak rupture. On the basis of calculations, fields of stresses? strains, rates of displacements of cross-sections of the rod in a plastic domain are determined. for a fixed instant of time, graphs of changes of stresses and displacements of points on the whole segment of a disturbed rod are plotted. The obtained results have been verified as to exactness of satisfaction to the boundary condition.
Impactand particle buffered vibration absorbers optimization and design
(Publishing House of Lviv Polytechnic National University, 2015) Diveyev, Bohdan
Passive, broadband targeted energy transfer refers to the one-way directed transfer of energy from a primary subsystem to a nonlinear attachment; this phenomenon is realized in damped, coupled, essentially nonlinear impact or particle dynamic vibration absorber (DVA). An impact damper is a passive control device which takes the form of a freely moving mass, constrained by stops attached to the structure under control, i.e. the primary structure. The damping results from the exchange of momentum during impacts between the mass and the stops as the structure vibrates. A particle-based damping system can overcome some limitations of ordinary DVA by using particles as the damping medium and inter- particle interaction as the damping mechanism. Large damping at such family constructions of DVA’s does not bring to destruction an elastic DVA element over in critical cases, when working frequency approaches own frequency of DVA, or when the transitional process of acceleration of rotating machines is slow enough and DVA’s has time to collect large amplitudes of vibrations. The primary structure is modelled as a spring-mass system. In this paper, an efficient numerical approach based on the theoretical-experimental method is proposed to maximize the minimal damping of modes in a prescribed frequency range for general viscous tuned-mass systems. Methods of decomposition and numerical synthesis are considered on the basis of the adaptive schemes. The influence of dynamic vibration absorbers and basic design elastic and damping properties is under discussion. A technique is developed to give the optimal DVA’s for the elimination of excessive vibration in sinusoidal forced rotating system. It is found that the buffered impact damper not only significantly reduces the accelerations, contact force and the associated noise generated by a collision but also enhances the level of vibration control. The interaction of DVA’s and basic design elastic and damping properties is under discussion. One task of this work is to analyze parameters identification of the dynamic vibration absorber and the basic structure. The discrete-continue models of machines dynamics of such rotating machines as water pump with the attachment of particle DVA’s and elongated element with multi mass impact DVA’s are offered. A technique is developed to give the optimal DVA’s for the elimination of excessive vibration in harmonic stochastic and impact loaded systems.
Зміст до "Ukrainian Journal of Mechanical Engineering and Materials Science" Volume 1, number 1
(Publishing House of Lviv Polytechnic National University, 2015)
Causes of ductility-dip cracks formation In In52 and In52 MSS alloys during fusion welding
(Publishing House of Lviv Polytechnic National University, 2015) Beliaiev, Grigorii; Volosatov, Ivan; Kakhovskyi, Mykola
The aim of the paper is to investigate one of the causes of ductility-dip cracks (DDC) formation. The main aim of this work is calculation of grain boundaries (GB) cohesive energy in nickel based In52 and In52 MSS alloys. For measuring the GB energy anisotropy methods of thermal etching and light interferometry were used. DDC form on the grain boundaries of nickel based alloys due to adsorption of impurities during multipass welding. The In52 alloy has tendency to form DDC during multipass welding fusion unlike In52 MSS one doped with Mo and Nb. The main cause is the change of thermodynamic state of the GB, as it is indicated by the decrease in the cohesive energy to 1.8-1.26 J/m2. During multipass fusion welding in In52 alloy adsorption of S and O from the grains body to GB takes place. The average concentration of O and S on the surface of DDC for high angle boundaries is within 2.3-4.5 and 0.5-1 at. %, respectively. Presented in this paper results have shown the influence of welding heat for reduce the cohesive strength of GB and, as a result, of the formation of DDC. Quantitative effect of S and O as embrittlement elements on the value of decrease in the cohesive energy was shown.
Fundamentals of creation of newdevices for speed change management
(Publishing House of Lviv Polytechnic National University, 2015) Malashchenko, Volodymyr; Strilets, Oleh; Strilets, Volodymyr
The article deals with problem of speed change management in engineering, i.e., hoisting, building, road and land reclamation machines, cars and tractors, machine tools and other equipment. The review of the methods and devices for stepped, steppless and combined speed change process management have been performed. Their major disadvantages have been identified. Among others, main disadvantages of stepped speed management devices are the complexity of design, their large material consumption, the emergence of dynamic loads during the transition from one speed to another, even in case of synchromesh using. Continuously variable speed devices have intense components wear due to the use of friction connections like brakes or lock-up clutches. The authors lead to the conclusion about the need for new devices of speed change management to remove, or at least decrease, identified deficiencies. New devices suggested for speed changes management via epicyclic gear trains with a closed circuit hydrosystem. Those new constructions are supposed to remove abovementioned shortcomings and can be the basis and foundation for new devices creation and their further research.
Ways of improvement of technological process of copper wire rod production
(Publishing House of Lviv Polytechnic National University, 2015) Dvoryanyn, Hrystyna; Shvachco, Sergiy
Copper is a unique chemical element which is used since ancient times due to its universal chemical properties. By means of the method of continuous founding, hundreds of items of rod-like billets of different cross-section shapes are manufactured from copper. The problem of production of defectfree copper wire rods is important nowadays, because the market of cable products still increases. As the deposits of cooper ore in the nature are being exhausted, the processing of copper scrap becomes of still growing interest for non-ferrous metallurgy. There emerged the necessity of further study and improvement of the technology of production of copper wire for electrical engineering and that of copper wire rods. In manufacturing of copper wire rods according to the method of continuous founding, there emerge violations of technological process because of formation of hot cracks in a cast billet. Just for this reason, in this article, such problems are described, and ways of their solving are considered. The character of their structure formation during crystallization of copper wire rods is analyzed. Advantages and drawbacks of the method of continuous founding of copper wire rods are described. The possibility of the use of ultrasonic oscillations for improvement of the quality of finished products is shown.
Robust mechanical system swith mechatronic devices: parameters identification and vibration control
(Publishing House of Lviv Polytechnic National University, 2015) Chovnyuk, Yurii; Dikterjuk, Mykhailo
The disturbance estimated with the help of advanced mechatronic devices is used for realization of robust mechanical system, such as agricultural machines. In the actual application, the estimated disturbance is effective not only for the disturbance compensation but also for the parameter identification in the mechanical system. The identified external force is applicable to sensorless force feed-back control in mechanical system and is utilized for a realization of mechanical vibration control. The progress of robust control technologies makes it possible to realize high performance motion control. In the industrial drive system such as a modern agricultural machine with advanced mechatronic device system for motion control, however, the developed technology is not enough to obtain the stable and high speed motion response since the mechanical vibration arises under the high accuracy positioning control. The mechanical vibration control is also taken in the field of the motion control. In particular, a vibration control based on the external force feedback brings the sophisticated advantages to the mechatronic system. The paper introduces a vibration control strategy based on the external force feedback called “resonance ratio control” in multiple resonance system. In this case, the external force may be obtained by using the identification process.
Synthesis of structure and research of operation of resonance two-mass vibrating table with electromagnetic drive
(Publishing House of Lviv Polytechnic National University, 2015) Lanets, Oleksiy; Borovets, Volodymyr; Lanets, Olena; Shpak, Yaroslav; Lozynskyy, Vasyl
An industrial necessity of creation of 100-Hz vibratory tables is grounded. The prospect of researches of just resonance electromagnetic vibratory tables is conditioned. The existing vibrating tables on the basis of electromagnetic drive are considered. It is noted that the stages and problems which arise during the creating of high-frequency two-mass vibration table of middle sizes constructed according to classic chart are oulined in the article. The principle scheme of an electromagnetic vibratory table which is to be developed is described. The basic analytical dependences for determining the coefficient of inflexibility of the resonance resilient system and hauling effort of the electromagnetic vibroexciters are obtained. The construction of the upper plate of vibrating table is grounded, and its first eigenfrequency is determmined in order to avoid the coincidence with its forced frequency. The construction of vibrating table is given: its spatial model is presented, and the general draft and the draft of the two-mass vibratory system are also given. The inertia parameters of the oscillating masses are determined. The parameters of stiffness and structural parameters of the resonance resilient system are determined. Checking of the resilient elements for durability is conducted. The parameters of stiffness and structural parameters of vibration isolators are determined. The results of calculation of vibroexciter, according to the hauling effort with the use of the specially developed program, are presented. The theoretical gain-frequency description of vibratory table and time dependences of motion of the oscillating masses are presented. The experimental gain-frequency description of vibratory table and time dependences of motion of the oscillating masses, which absolutely coincide with the theoretical, are presented.
Nonlinear analysis in synthesis of the resonant vibro-impact systems
(Publishing House of Lviv Polytechnic National University, 2015) Gursky, Volodymyr; Kuzio, Ihor
The paper considers differential equation of the vibro-impact resonance system with an asymmetric piecewise linear elastic characteristic. The time-instant of switching of elastic characteristic is determined on the basis of equality of oscillation period to average value of the corresponding eigenfrequencies. Then, expansion of the asymmetric piecewise linear elastic characteristic into Fourier series was made. The initial differential equation was reduced to a kind of parametric equations of Hill’s andMathieu’s type with taking into account the time of elastic characteristic change. Stability analysis of parametric Mathieu equation is shown for the analysis of natural oscillations. For stability analysis of the synthesized by various stiffness coefficients of vibro-impact system, dependencies of Mathieu equations coefficients on the parameter of synthesis are used. The solution of the initial equation with forced oscillations in the form of asymmetric two-frequency vibrations has been obtained by means of Bubnov-Galerkin and Levenberg-Marquardt methods for nonlinear algebraic systems of equations, also amplitude and phase frequency dependence was graphically drawn. The basic equation with an asymmetric elastic response characteristic feature is determined by the fixed natural frequency of oscillations independently of amplitude. Numerical solution of differential equations by means of Runge–Kutta method are presented for comparison. Comparison of the vibro-impact resonance system kinematics characteristics, synthesized by the elastic parameters and solved by the listed methods, is conducted. The feasibility of using nonlinear analysis presented in two harmonics in Fourier series asymmetric elastic characteristic is justified in the article. The suggested approach with Bubnov-Galerkin method for general Hill’s equation and correlation analysis of time kinematic characteristics was used. Acceleration frequency spectrum and harmonics are obtained on the basis of Runge–Kutta numerical method simulation of the initial nonlinear differential equation.
Analysis of structure and kinematics of four-bar crank-rocker walkingmechanism
(Publishing House of Lviv Polytechnic National University, 2015) Korendiy, Vitaliy
Problems and prospects of using the walking mode for producing motion of robotic systems are considered. Advantages and spheres of the use of mobile robotic systems equipped with walking movers are substantiated. Preferences of cyclic (lever) walking mechanisms are analyzed. The kinematic parameters of four-bar crank-rocker walking mechanism, constructed on the basis of Chebyshov-Umnov mechanism, are accepted as the subject of research. The process of motion of the supporting foot of the walking mechanism is accepted as the object of research. The main aim of the investigation consists in carrying out structure and kinematics analysis of the mentioned mechanism with further derivation of analytical dependencies for calculating kinematic parameters of the supporting foot motion. The special features of the structure of four-bar walking mechanism and theoretical foot loci (paths) are considered. The form of the most reasonable path for further research is established. As a result of carried out structure analysis, it is ascertained that the mechanism consists of two structural groups: that of the first class and that of the second class second order first type. As a result of kinematics analysis, the analytical expressions for calculation of coordinates of the supporting foot hinge of the walking mechanism depending on geometric parameters of the mechanism and the angle of the crank rotation are deduced. The prospects of further investigation under the themes of the paper are analyzed. In particular, the goal function, which may be used for further optimization of structural parameters of the mechanism, is considered and the use of applied software for solving optimization problem is suggested. The optimization problem consists in evaluating such geometric parameters of the walking mechanism which allow the motion of the supporting foot in accordance with the prescribed (specified) path.
Modification of surfaces of special alloys by nitrogen for power engineering
(Publishing House of Lviv Polytechnic National University, 2015) Duriagina, Zoya; Tepla, Tetiana
The use of nitrogen as an alloying element presents a great interest for the improvement of properties of alloyed steels and special alloys. Superficial layers were formed by ionic implantation and by melting the surface by nitrogen plasma. After this kind of treatment, there form a continuous defect-free layers with a good adhesion to the surface. Surface treatment of steels and vanadium alloys increases their corrosion resistance and microhardness of surface layers. A combined supply of alloying elements into the melting area allows us to control the type and the density of secondary phases which are formed as the result of the reaction diffusion. In this way, depending on external needs, it is possible to increase either corrosive-electrochemical properties of the surface (when alloyed layers consist mainly of nitride or oxinitride phases) or wear resistance (when carbide or carbonitride phases will constitute a greater specific volume in the formed layers).
Micromechanical properties and thermal annealing of zinc oxide bulk ceramic
(Publishing House of Lviv Polytechnic National University, 2015) Virt, Ihor; Pavlovskyy, Yuriy; Hadzaman, Ivan
Zinc oxide has numerous commercial device applications. Polycrystalline ZnO varistors, for example, are widely used in high voltage and power-related applications in industries such as microelectronics. One of the ways to control the properties of ZnO is its annealing in various environments, including oxygen, which leads to increased hardness and fracture toughness of ceramics. Therefore, the study of micromechanical properties of materials for modern electronics is an important and vital issue, both in terms of technology for improving quality of the final product and from the point of view of prospect of its practical use. The structural properties of the ceramic samples of ZnO have been studied. The average grain size has been defined. The micromechanical properties have been studied. The temperature conditions of increasing microhardness of ZnO have been defined after annealing in an oxygen atmosphere.
The phase difference between components of elliptical oscillations of vibratory conveyor providing maximum conveying velocity
(Publishing House of Lviv Polytechnic National University, 2015) Vrublevskyi, Іgor
The piece goods conveying by the vibratory conveyor with elliptical oscillations is considered. Elliptical oscillations of the conveyor track are realized when conveyor has independent drives of oscillations in the direction of conveying (longitudinal oscillations) and oscillations in the direction perpendicular to conveying plane (normal oscillations) with phase difference between them. Elliptical oscillations allow increasing conveying velocity and inclination angle of conveyor track in comparison with the simplest linear oscillations. Conveying velocity of parts moving along the track of conveyor varies with the change of phase difference angle and reaches a maximum with a certain angle, depending on several different parameters. This angle is called the optimal phase difference angle, and it depends on the amplitudes and frequency of the component oscillations, the track inclination angle, the frictional properties, impact parameters of conveying parts. As the experimental investigations have shown, the piece goods conveying is quite accurately described by the theory of a massive point particle moving on an inclined plane under the action of vibration. A system of nonlinear differential equations describing the conveying in continuous contact modes and in modes with hopping was composed. This system has been solved by gradual integration method with numerical calculation with any desired accuracy. This allowed us to study the dependence of conveying velocity on different parameters in the form of graphs. And for greater generality the study was conducted in dimensionless parameters. There were studied in detail the influence of dimensionless parameters on dimensionless velocity – the coefficient of velocity that is the ratio of conveying velocity to amplitude of longitudinal oscillations with a constant frequency. To verify the obtained dependences, the experimental investigations of conveying velocity were carried out on vibratory conveyor with removable tracks. The conveyor was fastened on the turntable, the inclination of which was varied by a screw jack. The amplitude of the component oscillations was varied by changing voltage applied to the electromagnetic drives, the phase difference between component oscillations was varied by the phase shifter. Waveforms of oscillations were recorded by vibration measurement equipment. The coefficient of friction was measured directly during conveying. The velocity was measured by the stopwatch. The comparison of experimental results with theoretical data has shown the excellent agreement in continuous contact modes and the acceptable match in modes with hopping. Based on the obtained graphs, the approximate formulas for calculating velocity and optimal phase difference angle were derived. The influence of frictional properties of the conveying parts, namely, the coefficient of friction on optimal in terms of velocity phase difference angle between the longitudinal and normal components of the elliptical oscillations is investigated. It is shown that the optimal phase difference angle decreases with the increase in the coefficient of friction. The approximate formula of optimal phase difference angle dependence on the coefficient of friction and track inclination angle is derived.
Development of welding consumables for wet underwater welding of high-alloy corrosion-resistant steel
(Publishing House of Lviv Polytechnic National University, 2015) Kakhovskyi, Yurij; Kakhovskyi, Mykola
This paper discusses a technology of mechanized wet underwater welding of high-alloy corrosion-resistance steel. The main aim of the investigation is development of self-shielded flux-cored wire for wet underwater welding for the first time in the world practice. A mathematical method of experiment design was used for determination of quantity and quality characteristics. Besides, quantitive and qualitative indices of welding-technological characteristics such as weld metal gas saturation, stability of arc burning in water medium, and optimum composition of gas-slag-forming components of flux-cored wire charge were determined. Problems of this branch and current ways of performance of welding – repair operations on objects of high-alloy corrosion-resistance steel were outlined. Application of experimental self-shielded flux-cored wire in mechanized wet underwater welding of high-alloy corrosion-resistance steel allows increasing efficiency and quality of underwater welding-repair operations and receiving economical effect due to reduction of production downtime of object under repair. Usage of present technology provides for the possibility of complete elimination or partial reduction of human participation in welding process under extreme conditions in radioactive environment (in the case of NPP) and in welding at greit depth. The results of researches can be used for weldingrepair operations in nuclear power plants, for ship repair and ship-raising operations and on hydraulic structures. Proposed innovation technology allows complete replacement of wet underwater welding using coated electrodes as well as eliminating human participation in welding-repair operations of critical structures under especially dangerous conditions such as underwater welding.