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U teorijskom dijelu rada opisane su konstrukcijske karakteristike igličastih ležaja, hidrodinamičke pojave u njihovom podmazivanju te metode ispitivanja maziva, vibracija, buke i zagrijavanja. U eksperimentalnom dijelu provedeno je nitriranje unutarnjeg ležaja igličastog ležaja izrađenog od čelika EN DIN 100Cr6 postupcima TENIFER i plazma nitriranje. Različitim postupcima nitriranja dobivene su površine sa i bez sloja željeznih nitrida. Nakon nitriranja provedena su ispitivanja hrapavosti površine, tvrdoće površine, te ispitivanje metodom klizanja prizme po prstenu. Metodom klizanja prizme po prstenu ispitani su utjecaji nitriranja površine, brzina vrtnje i dodavanja maziva na pojavu traga trošenja, promjenu kinetičkog trenja i zagrijavanja, te pojavu buke i vibracija. Za provedbu ispitivanja korišteno je suncokretno ulje i sintetičko motorno ulje SAE 5W-30. Iz provedenih ispitivanja utvrđeno je da je do pojave najmanje prosječne širine traga trošenja došlo u uvjetima podmazivanja uljem SAE 5W-30 kod tribopara „PN480 – ležajna bronca“. Do pojave najmanje prosječne vrijednosti faktora trenja došlo je u uvjetima podmazivanja suncokretovim uljem. Pri manjim brzinama kod tribopara „PN480 – ležajna bronca“, a pri većim brzinama kod tribopara „EN DIN 100Cr6 – ležajna bronca“. Analiziranje buke tijekom ispitivanja utvrđeno je da korištenjem podmazivanja dolazi do smanjenja buke i ujednačenijeg rada. The theoretical part of the paper describes the structural characteristics of the needle bearings, hydrodinamic phenomena in their lubrication and methods of testing lubricants, vibrations, noise and temperature changes. In the experimental part, nitriding of the inner ring of the needle bearing made of EN DIN 100Cr6 steel was carried out using TENIFER and plasma nitriding processes. Various nitriding processes were used to obtain the surface with and without the formation of a layer of iron nitrides. After nitriding, tests of surface roughness, surface hardness and block on ring test method were conducted. Using the block on ring method the effects of surface nitriding, speed of the rotation and addition of the lubricant on the appearance of wear marks, changes in kinetic friction and temperature changes with the appearance of noise and vibrations were tested. Sunflower oil and synthetic motor oil SAE 5W-30 were used for the lurication during the tests. From the conducted test s, it was determined that the appearance of the smallest average width of the wear marks occurred under the conditions of lubrication with the SAE 5W-30 oil in the tribopair „PN480 – bearing bronze“. The lowest average value of the friction factor occurred under the conditions of lubrication with the sunflower oil. It occurred at the lower speeds in the tribopair „PN480 – bearing bronze“ and at a higher speed in the tribopair „EN DIN 100Cr6 – bearing bronze“. Analyzing the noise during the tests, it was determined that the use of the lubrication leads to a reduction of noise and uniform operation. |
