Journal of Engineering Sciences / Журнал інженерних наук
Permanent URI for this collectionhttps://devessuir.sumdu.edu.ua/handle/123456789/34326
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Item Increasing the contact strength of Bohler K490 MicroClean steel parts by determining carbonitriding conditions(Sumy State University, 2025) Довгополов, Андрій Юрійович; Dovhopolov, Andrii Yuriiovych; Колесник, Віталій Олександрович; Kolesnyk, Vitalii Oleksandrovych; Панченко, Андрій Васильович; Panchenko, Andrii Vasylovych; Некрасов, Юрій Олександрович; Nekrasov, Yurii Oleksandrovych; Дегтярьов, Іван Михайлович; Dehtiarov, Ivan Mykhailovych; Šimna, V.; Проскурня, Сергій Іванович; Proskurnia, Serhii Ivanovych; Чумаков, Дмитро Сергійович; Chumakov, Dmytro SerhiiovychThe problem of increasing the service life of various devices and units operating under high loads on parts remains open to date. Increasing the service life of these mechanisms is possible by increasing the contact strength of the material. Various thermal and chemical-thermal treatment (CTT) methods are often used to improve this parameter. This work presents the results of an experimental study of the influence of CTT parameters on the contact strength of the surface layer of high-quality powder steel Bohler K490 MicroClean. The study’s relevance is due to the need to increase the wear resistance and durability of parts of tools and machines operating under challenging conditions. The primary purpose of the work was to determine rational temperature-time conditions of carbonitriding to ensure maximum surface hardness and effective depth of the hardened layer. The research methodology included sample preparation, heat treatment, machining using Tenifer-QPQ technology at 560, 580, and 610 °C, and holding for 1–6 h. The Vickers method measured the microhardness, the carbonitrided layer depth was determined, and metallographic analysis of the microstructure was performed. The results showed the best combination of high surface hardness (up to 1434 HV0.2) and sufficient hardening depth at a temperature of 580 °C and a holding time of 6 h. Pre-hardening positively affects the formation of a dense zone, strengthening the surface layer. On the contrary, an increase in temperature to 610 °C led to a deepening of the diffusion layer, but was accompanied by a decrease in the hardness of the core. The results of this study were implemented in the practice of a machine-building enterprise in the Sumy region of Ukraine, which specializes in thermal and CTT of parts of various types.Item Contact of working surfaces for spherical washers and recommendations for determining the gap in the joint(Sumy State University, 2020) Дегтярьов, Іван Михайлович; Дегтярев, Иван Михайлович; Dehtiarov, Ivan Mykhailovych; Нешта, Анна Олександрівна; Нешта, Анна Александровна; Neshta, Anna Oleksandrivna; Samardak, M.P.; Antosz, K.; Avramenko, S.E.In article analyzes the technical requirements for spherical washers used in threaded connections of pumps, which made it possible to highlight contradictions in paragraphs of the current standards for pump fasteners. They regarding recommendations for manufacturing technology and control of the working surfaces of washers. Publication analysis in the spherical surfaces lapping showed the absence of research in the spherical surfaces contact after lapping and the dependence of contact parameters by the technological parameters for this operation. The presence of a gap in conjunction with spherical washers after the lapping process was proved geometrically. Its location was determined, and a mathematical dependence was obtained to determine the maximum gap value in conjunction. It was found that the gap depends on the design parameters of the washers' conjunction and the abrasive material grain size used for lapping. Recommendations for selecting the abrasive material grain size for the lapping operation for the most common values of the roughness parameters for the working surfaces of spherical washers have been formed. In the article was proposed to introduce into the technical requirements for the spherical washers drawings changes concerning the gap size allowable in the conjunction, and as well as tolerances value changes of the radii of the working surfaces of the washers, thus increasing their manufacturability without conflicting with the requirements of the current standards.