Search Results (4)

A comprehensive experimental investigation of the wear behaviour of coated spur polymer gears made of POM is performed in this study. The three physical vapour deposition (PVD) coatings investigated were aluminium (Al), chromium (Cr), and chromium nitrite (CrN). Al was deposited in three process steps: By plasma activation, metallisation of Al by the magnetron sputtering process, and by plasma polymerisation. Cr deposition was performed in only one step, namely, the metallization of Cr by the magnetron sputtering process. The deposition of CrN was carried out in two steps: the first involved the metallization of Cr by the magnetron sputtering process while the second step, vapour deposition, involved the reactive metallisation of Cr with nitrogen, also by the magnetron sputtering process. The gears were tested on an in-house developed testing rig for different torques (16, 20, 24 and 30 Nm) and rotational speed of 1000 rpm. The duration of the experiments was set to 13 h, when the tooth thickness, and, consequently, the wear of the tooth flank was recorded. The experimental results showed that the influence of metallisation with aluminium, chromium, and chromium nitrite surface coatings on the wear behaviour of the analysed polymer gear is not significant. This is probably due to the fact that the analysed coatings were, in all cases, very thin (less than 500 nm), and therefore did not influence the wear resistance significantly. In that respect, an additional testing using thicker coatings should be applied in the further research work. Full article

Energy efficiency and functional reliability are the two key requirements in the design of high-performance transmissions. Therefore, a representative analysis replicating real operating conditions is essential. This paper presents the thermoelastohydrodynamic lubrication (TEHL) of meshing spur gear teeth of high-performance racing transmission systems, where high generated contact pressures and lubricant shear lead to non-Newtonian traction. The determination of the input contact geometry of meshing pairs as well as contact kinematics are essential steps for representative TEHL. These are incorporated in the current analysis through the use of Lubricated Loaded Tooth Contact Analysis (LLTCA), which is far more realistic than the traditional Tooth Contact Analysis (TCA). In addition, the effects of lubricant and flash surface temperature rise of contacting pairs, leading to the thermal thinning of lubricant, are taken into account using a thermal network model. Furthermore, high-speed contact kinematics lead to shear thinning of the lubricant and reduce the film thickness under non-Newtonian traction. This comprehensive approach based on established TEHL analysis, particularly including the effect of LLTCA on the TEHL of spur gears, has not hitherto been reported in literature. Full article

This paper presents the results of a conducted topology management optimization study based on the finite element analysis on a two-stage spur gear reducer housing body and cover using the SOLIDWORKS Simulation module. The main goal of the study is to optimize the overall weight of the reducer by thinning specific areas of the casted gearbox housing elements according to the calculated minimal strain energy. The topology optimization algorithm that is used in current research gives an optimal structural shape of the housing elements of the reducer with the largest stiffness, considering the given amount of mass that will be removed from the initial design space. The complete sequence of steps for conducting the topology management optimization study is shown, taking into account the constraints arising from the construction features and the method of manufacturing the housing elements of the gear reducer. Conclusions on the use of the topology optimization results are given and potential directions for further development of the approach are also identified. Full article

The gear is a cyclic symmetric structure, and each tooth is subjected to a periodic mesh force. These mesh forces have the same phase difference tooth by tooth, which can excite gear vibrations. The mechanism of additional axial force caused by gear bending is shown and examined, which can significantly affect the stability of a self-excited thin spur gears vibration. A mechanical model based on energy balance is then developed to predict the contribution of additional axial force, leading to the proposed numerical integration method for vibration stability analysis. By analyzing the change in the system energy, the occurrence of the self-excited vibration is validated. A numerical simulation is carried out to verify the theoretical analysis. The impacts of modal damping, contact ratio, and the number of nodal diameters on the stability boundaries of the self-excited vibration are revealed. The results prove that the backward traveling wave of the driven gear as well as the forward traveling wave of the driving gear encounter self-excited vibration in the absence of sufficient damping. The model can be used to predict the stability of the gear self-excited vibration. Full article