Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Mechanical Design of a Reduced FZG Tribometer with Variable Loading
Submission Author:
Lenine Marques de Castro Silva , RN , Brazil
Co-Authors:
Lenine Marques de Castro Silva, Aylla Maria de Moura Alencar Rocha, Adilson Oliveira, Salete Alves
Presenter: Salete Alves
doi://10.26678/ABCM.COBEM2021.COB2021-1094
Abstract
In order to contribute with the tribological studies of the contact between gear teeth and improve their efficiency, a detailed mechanical design of an FZG tribometer based on DIN ISO 14635-1: 2000 was developed. The FZG tribometer consists of two parallel gearboxes connected by two parallel shafts forming a back-to-back power recirculation system. One of the shafts is called driving shaft and the other one is called driven shaft. The presented tribometer, however, has considerable limitations for applications in academy: 1) the need of 1,25 liters of oil per box at each test; 2) the load application is carried out in a totally static way (needing to stop the test to apply new load stages); and, therefore, 3) a non-viability of an automated test. For the purpose of work out the first problem, a scale reduction was planned for the project. The reduced components shall require no more than 100 ml to lubricate each gearbox per test. This improvement enables the use of lubricating oils with nanoadditives, whose production is limited to small amounts of oil. In furtherance of a loading system more realistic and practical a third shaft, called loading shaft, was developed to increment the FZG tribometer. The new shaft carries a disk brake system, which is applied by standardized masses, and a torque transmitting system composed of a chain and two sprockets. Thus, it is possible to increase the load without stopping the machine and future increments shall enable the application of dynamic loading by mechanical actuators. In addition, the substitution of the loading elements on the driven shaft for a parallel loading system sets up the discussion around the possibility of simultaneous testing under identical loading conditions. In this way, it is also possible to use cylindrical helical gears without changing the design of the bearings, since, the axial component forces generated by the helical gears pairs cancel each other when the helical gears pairs are placed in a parallel and opposite layout regarding one to another. The project also has a frequency inverter which keeps the angular velocity under control despite the charge that is applied on the loading system and enables the further automation of the test. Finally, it was possible to deduce from the calculus that the scale reduction of the project did not compromise the expected Hertz values on the contact between the gears teeth guaranteeing the development of contact fatigue.
Keywords
mechanical design, gears tribology, FZG test, oil load capacity, Variable Load
