Obtenção de curvas de stribeck em sistema tipo mancal de deslizamento
Over the years, the improvement of machinery and the search for maximum efficiency lead to the development of the field of tribology, the science in which the interaction between friction, wear and lubrication is studied. The goals of the present work were: the assesment of Stribeck’s Curves and, co...
| Principais autores: | Shinmi, Alexandre Vatanabe, Maximiano, Raphael Cesar |
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| Formato: | Trabalho de Conclusão de Curso (Graduação) |
| Idioma: | Português |
| Publicado em: |
Universidade Tecnológica Federal do Paraná
2020
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| Assuntos: | |
| Acesso em linha: |
http://repositorio.utfpr.edu.br/jspui/handle/1/10269 |
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| Resumo: |
Over the years, the improvement of machinery and the search for maximum efficiency lead to the development of the field of tribology, the science in which the interaction between friction, wear and lubrication is studied. The goals of the present work were: the assesment of Stribeck’s Curves and, consequently, the development of a methodology for obtaining them and the improvement of the current configuration of a Kinetic Friction Machine (Máquina de Atrito Cinético - M.A.C. - in portuguese). The tests were performed using a tribological set lubricated with Lubrax Top Turbo oil, 15W40, manufactured by Petrobrás. This set was composed by a counter specimen (in portuguese CCP) made of machined SAE 1020 steel and a commercial sliding bearing specimen (CP) manufactured by MAHLE Metal Leve AS. 12 valid tests were performed with an average durantion of 3.5 hours each, with loads of 40,7N, 55,4N and 72,7N divided into 3 batteries with 4 runs per battery. The friction coefficients were analysed at six rotation speeds (starting from 2500, 2000, 1500, 1000, 500 to 250 rpm) with a 35 minute period for each speed. That is the time needed in order to reach steady state and to allow the measurement of the friction coefficient in each given situation. The obtained data were analysed and used to plot the Stribeck’s Curves. As a result, it was proved that the “M.A.C.” is able to conduct tests for this purpose as long as the test parameters are within the operating range. Its limits are related mainly to vibration at high speeds (above 2500 rpm) and the difficulty for setting a specific rotation in low speeds (below 250 rpm). Regarding the parameters monitored in the tests, it was observed that the shaft rotation speed has a significant influence over the oil flow, which impacts the lubricant’s inlet temperature. Due to the changing in the oil’s temperature, viscosity also changed and, despite the implementation of an oil heating system, it was not possible to control the inlet temperature over the entire rotation range. Consequently, the Stribeck’s Number values were affected in some situations. When plotted together, the 4 Stribeck’s Curves obtained in the same condition were slightly diferent due to these discrepancies. Because of these factors and the changing of loads the composition af a single Stribeck’s Curve was not considered to be suitable. |
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