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Technológ - celé číslo 3/2024
(University of Žilina, 2024)
Vplyv technológie tepelného spracovania na tribologické vlastnosti vybraných oceľových materiálov
(University of Žilina, 2024) Harvanec, Jakub; Mičian, Miloš; Nový, František
The heat treatment technology changes all sorts of materials properties. We examined the change of tribological properties of selected powder metallurgy materials and conventional steels, in this article. We used special testing equipment, for measuring the changes of friction coefficient of individual tested materials, before application of the heat treatment and after application of the heat treatment. We tested two types of powder metallurgy steels and two types of conventional steels. The changes in friction coefficient are shown in the table and charts. We used boronising, nitriding and surface hardening as procedures of heat treatment.
Analýza vlastností medených drôtov vyrobených pretlačovaním
(University of Žilina, 2024) Bílik, Jozef; Sobota, Róbert
The article focuses on the production of copper wires by extrusion and the evaluation of their mechanical properties. The article presents the results obtained on the basis of tensile tests and on the basis of hardness measurement. The tests were carried out on a semi-finished product with a circular cross-section and on manufactured wires with a rectangular cross-section. The wires produced were 9.5x4.5 mm, 10.5x1.65 mm and 5.75x1.35 mm. The impact of the transformation on the microstructure of the produced wire was also monitored.
Hodnotenie pohodlia jazdy v osobnom vagóne prostredníctvom rovinného dynamického modelu pri zvislom kmitaní
(University of Žilina, 2024) Dižo, Ján; Lovska, Alyona; Blatnický, Miroslav; Ishchuk, Vadym
The presented research is focused on a derivation of a mathematical model of a passenger wagon based on a dynamical model in a plane with three degrees of freedom. Vertical oscillation of a passenger wagon is calculated in two different software, namely Matlab and Simpack. It is considered that three degrees of freedom are defined as following: a vertical deflection of a front bogie frame, a vertical deflection of a rear bogie frame (in a running direction) and a vertical deflection of a wagon body. The Lagrange’s equations of the second kind method is used for a derivation of the equations of motion, i.e. for a derivation of a mathematical model of wagon oscillation. Subsequently, the derived equations of motion are solved in the Matlab software as well as in the Simpack software. Both software apply calculation in a time domain. Evaluation of the results is focused on an investigation of ride comfort for passengers. This ride comfort is expressed by the NMV index calculated in five points on a wagon body floor. These calculations come from the formulation defined in the corresponding standard. The results of the NMV indices are presented in the bar graphs based on the numerical values of the NMV indices.
Hodnotenie celistvosti zváraných potrubných zostáv z plastu kombinovanou skúškou pevnosti a tesnosti
(University of Žilina, 2024) Koňár, Radoslav; Grünermelová, Lucia; Mičian, Miloš; Leždík, Viliam
The welding of plastic pipes during the reconstruction and construction of new gas networks is often accompanied by non-compliance with technological discipline. One of the prominent problems in the verification of the quality of the work performed is connected with non-compliance with the technological discipline, namely the correct application of the strength and tightness test. Strength and tightness tests are often applied not according to a correctly approved testing methodology. These checks are often carried out inexpertly. This results in the identification of small gas leaks only when the leak checks are subsequently carried out in connection with additional interventions on the pipelines, such as repairs, installation of a branch, transhipment, reconstruction, etc. The leaks are located in the places of the original pipeline in the ground. However, most of the identified leaks arose during the implementation of the original gas pipeline networks, and not as an operational defect. These defects were not identified due to the incorrect application of the tightness test before the gas pipeline was put into operation.