Ukrainian Journal of Mechanical Engineering and Materials Science
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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 UniversityThe 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.Item Strengthening and reconstruction of drilling core pipe for engineering and geological exploration(Видавництво Львівської політехніки, 2022-02-22) Dzyubyk, Andrij; Dzyubyk, Liudmyla; Shpak, Bohdan; Lviv Polytechnic National UniversityCurrently, there is a tendency to increase the depth of gaseous and liquid fossils extraction. Therefore, prospecting and developing new deposits is promising. There is also a need to create new freshwater sources and implement relevant geological work based on this need. It is essential to have information about the characteristics of the explored slabs and the geology of the fields in general. Implementation of engineering and geological core drilling exploration is the most acceptable and provides the necessary data. Here, the peculiarities of the technological schemes of the process implementation make it possible to obtain separate sections of structures at a depth of the drilling equipment. It is essential to use traditional equipment, recommended for decades and provides the necessary results [1–3]. In the drilling process, you can achieve different diameters and depths of wells execution, obtain fossil samples etc. Engineering and geological exploration drilling is now taking on increased use in various industries [3]. Therefore, the problem of providing highquality drilling tools, the stability of their operating characteristics, and the possibility of usage in different conditions is an urgent need today. Modern drilling problems determine the usage of components of the core set with the appropriate physical and mechanical characteristics. Especially it relates to elements close to the drilling tool and the place of fossil; destruction – drill pipe. It is installed immediately after the crown core drill and receives almost the same loads and effects during working [1–3]. Conditions for the implementation of the process of core drilling are characterized primarily by the effect on the elements of the significant axial and twisted core set forces. There is the influence of the corrosive and active environment of the fossil in the washing and lubricating liquids well, etc. High temperatures are also observed at the drilling sites [3], which negatively affect the working tool and speed up its operation. As a result, there is an intensive shock, and abrasive core pipe wear and operation indicators change their constructive size. As a result, it is necessary to replace the operated drill string periodically. Considering modern technical and economic factors, it may be decided to repair a pipe to its original size in many cases. There are tasks for providing the appropriate characteristics of the core pipe surface. It is possible to model such properties of the new surface that functionally the best meet the conditions of the drilling process of a given geological formation. The peculiarities of applying the therapeutic layer on the surface of the core pipe are investigated in work. The experience shows that using electric arc surfacing under the flux layer is expedient. This provides the necessary adhesion of the applied layer and promotes obtaining resistance to the operation surface of the core pipe. At the same time, there is high-quality protection and the possibility of additional alloying through the flux-slaggy welding bath. Using electrode powder type wires creates conditions for flexibility to achieve the established characteristics of functional layers [4–6]. The filling flux, located in the cross-section of the electrode wire, can be easily changed by chemical composition. At the same time, it is possible to make relatively small parties of a wire with the set characteristics. The technological scheme justification about the core pipe surfacing is performed. It provides the previous displacement of the electrode butt size from the zenith of the core pipe to prevent the welding bath from spreading. The structural pipe size , the requirements for residual deformations, and the conditions of shapping the welded layer show the practicality of welding on a helix.Item Design – technological optimization of the level of residual deformations during welding of pipe sections from PT-7m alloy(Lviv Politechnic Publishing House, 2021) Biloborodchenko, Volodymyr; Dzyubyk, Andrij; Dzyubyk , Liudmyla; Lviv Polytechnic National UniversityApplication of tubular elements in the chemical industry is widely used. The special properties of materials and their reaction to the welding thermal cycle is quite complex. This is especially true of titanium alloys, which when heated are sensitive to environmental influences, require special welding techniques and undergo residual welding deformations. The welded joints of tubular elements made of titanium alloy brand PT-7m, which undergo transverse deformations due to welding, are studied. It is necessary to ensure high-quality sealed welds. Analysis of the literature has shown that to obtain a guaranteed penetration it is necessary to increase the power of the arc discharge or perform multi-pass welding. This will provide larger cross sections of welded parts and should provide the specified strength characteristics. However, this technology, in turn, leads to an increase in residual deformation in the vicinity of the welded joint due to the intensive increase in the coefficient of linear expansion when heating the material. Also, the special thermophysical properties of titanium alloy such as increasing the affinity for gases when heated, increasing the grain size lead to a decrease in strength properties. In the presented work it is proposed to use a mechanical angular deformer with an indicator head and a reference base for the study of transverse residual deformations. Peculiarities of measuring sockets and methods of their preparation are revealed. A calculation scheme for determining the amount of deformation has been developed, which has been tested on flat welded specimens and transferred to tubular elements. The sequence of deformation measurement process is described and the peculiarities of their formation on flat samples and tubular sections are studied. The constructive decision of a welded joint of pipes which provides use of a compensation ring is offered. This approach allows to provide reliable protection of the root of the seam and its optimal formation with minimal residual deformation. At the same time it is possible to reach the reproducible form of a dagger of similar penetration in one pass. The result is a welded joint of the lock type, which is sealed and has a free formation of the seam root with high-quality protection by the gas atmosphere. The use of pulsed arc welding with a non-fusible electrode in an argon environment with filler wire allows to minimize the thermal impact on the base metal. Statistical processing of experimental data on the parameters of the welding mode and their influence on the residual transverse welding deformations is carried out. To obtain an unambiguous statistically reliable answer about the valid law of distribution of experimental data of the results of strain measurement, the balancing procedure and the development of an analytical pproximation distribution model are involved. It is shown that the measured values of the residual transverse deformation of the welded assembly are correctly described by the Laplace distribution, which predicts (probability not worse than 90 %) a decrease in the average value of the deformation value by 1.3 times.Item Features of repair welding of power hydrocylinder elements(Lviv Politechnic Publishing House, 2020) Dzyubyk, Andrij; Nazar, Ihor; Dzyubyk , Liudmyla; Lviv Polytechnic National UniversityAt present, the use of power hydraulic cylinders is an integral part of most industrial equipment. They provide translational and horizontal movements, replacement of goods, fixation, etc. These devices are necessary elements of the equipment where application of the corresponding level of effort is applied. Often hydraulic cylinders are created specialized to perform certain types of work. It should be noted that part of the elements of the power cylinder in the manufacture is combined with welding. Such integral connections provide rigidity of installation, tightness of a design, fatigue strength at multicycle loadings. Difficult operating conditions, significant workloads, the presence of various external factors often leads to the destruction of individual elements of the cylinder. At the same time, the cost of repairing equipment that involves replacement with new power devices is quite high. This causes the implementation of repair and restoration work carried out at specialized enterprises. However, in the case of repairs, there are often a number of problems that require prompt resolution in the production environment. These should include the provision of basic materials with similar physical and chemical properties, the establishment of welding modes, the selection of the necessary welding materials, the use of appropriate techniques for conducting the arc process, etc. Therefore the repaired welded design of the case of the power hydraulic cylinder needs additional studying for weldability of separate elements among themselves, formation of a zone of thermodeformation influence. In general, the repaired hydraulic cylinder should meet the installation operating requirements depending on the purpose. The design of the considered hydraulic cylinder of the press installation is rather technological from the point of view of maintenance of automation of welding process. It contains long welds of a simple ring configuration. At the same time, the significant linear dimensions and the presence of a cylindrical surface cause some complexity in the implementation of processes. The construction material of the power hydraulic cylinder is low-carbon low-alloy steels. The analysis of technological weldability indicates a tendency to crack due to the thermal cycle of welding. The simulation of welds of the power hydraulic cylinder is performed in the work. The number of rollers was taken into account when obtaining butt welds. A compa ative analysis of different electrode materials with different doping systems is done. The most applicable welding materials by chemical composition and properties of the weld metal are determined. According to the literature data and the results of comparative analysis, the optimal range of cooling rate of the main material of the hydraulic cylinder was established. The properties and structure of the zone of thermal influence of the butt welds of the power hydraulic cylinder have been studied. The magnitude of deformations and stresses caused by the thermal cycle of welding of the hell structure of the hydraulic cylinder liner is investigated. The admissible parameters of the zone of plastic deformations during butt welding are determined.Item Comprehensive approach to training specialists in the area of engineering education(Lviv Politechnic Publishing House, 2020) Dzyubyk, Andrij; Nazar, Ihor; Dzyubyk, Liudmyla; Mykhailinchyk, Ihor; Kulykovets, Yurii; Lviv Polytechnic National UniversityThe article outlines advantages of applying a comprehensive approach to training specialists in the area of engineering education. Modern approaches to project management in production are analyzed, using the known experience of the European countries and the world. The basic tools of project management that are applied at all stages of implementation of engineering projects are described. Based on the analysis of known project management techniques, it has been established that effective engineering project management is possible by way of involving future professionals in the stages from developing the project idea, goals and objectives to obtaining the desired results and achieving the set goals. It is important to motivate students to think critically and encourage teamwork on a project. In the present article, the authors suggest to consider the process of training specialists in civil and industrial engineering through the prism of the next four phases of the project. The first phase is to prepare the project with elements of structuring. It addresses the issues of the project goals, tasks and results, risk management, project documentation, budgeting, formation and management of the project team. The second phase is project management, which includes drafting a project structural plan (PSP) and work packages, scheduling task completion, resources and costs planning, cost estimation, and time management tools. The third phase is the implementation of the project with control and monitoring. Here, future specialists are working on issues of the project control, financial monitoring, monitoring of resources, communication and interaction between teams, conflict management, change management and keeping necessary documentation. Completion of the project is the fourth stage, which is an integral element of project management. It provides for financial and analytical reporting, documentation for retention of experience, knowledge management, certification and feedback to the project team. Based on teaching practice and considerable practical experience in industry, the authors found out that the process of pedagogical training of future competitive specialists in various areas of civil and industrial engineering should be accompanied by practical and theoretical materials on modern tools for a holistic and integrated approach to project management. At the same time, taking account of the dynamics of political and economic changes in Ukraine and integration with international standards, it is necessary to take a skilled approach to the issue of production change management in the project activity. The global experience reveals that only truly successful organizations anticipate and initiate changes. Thus, the organizations themselves, their goals, objectives and tools are undergoing changes. And the issue of change management itself is the subject for further research by the authors.