Análise da capacidade de carga do óleo de soja epoxidado na lubrificação de engrenagens com o auxílio de um tribômetro FZG modificado

Abstract

The purpose of this study is to measure the load capacity of epoxidized soybean oil in the lubrication of spur-toothed cylindrical gears. Therefore, a modified FZG tribometer was used, custom designed and built in the Tribology Study Group (GET) at the Federal University of Rio Grande do Norte (UFRN). The tribometer consists of two gearboxes, one being the driving, lubricated with a standard oil, and the other one being driven, lubricated with the oil to have its performance evaluated. For comparison purposes, tests were performed with a commercial mineral oil. The test procedure is based on the DIN ISO 14635- 1 standard, which consists in the gradual torque application on one of the tribometer axes, in order to promote a systematic increase in the Hertz contact pressure in the geared pair, as well as increased wear. Each test had 6 stages of loading, and the application of the loading was carried out by a system composed by caliper and brake disc. The first four stages are considered as running in stages. From stage 5 of loading, the initial temperature of the oil in the test gearbox must be 90°C ± 3°C, and during the test the oil temperature can vary freely. At the end of each test, the teeth of one gear from each gearbox were visually inspected using in order to observe the wear caused by scuffing or pitting. The tests were finished and considered concluded when the full width sum of damage to the active flanks of the pinion teeth exceeded the width of the gear tooth, or when the last load stage has been executed without meeting the above failure criteria. Thus, it was possible to verify that for this type of contact, the epoxidized soybean oil had a performance superior to mineral oil, widely used in the industry.