Ukrainian Journal of Mechanical Engineering and Materials Science

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Author: search.filters.author.Dzyubyk, AndrijSubject: search.filters.subject.hardening structures

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    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.
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    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 University
    Currently, 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.