Polymer Testing (Jun 2023)
The effect of center distance error on the service life of polymer gears
Abstract
Gear assembly errors are an important contributor to a premature gearbox failure. This study investigates the effects of center distance deviation on polymer gearbox life. The main focus was on the influence on the stress state of the gear. Reference spur gears (m = 1 mm, z = 20, b = 6 mm) with a standard involute gear profile and a gear ratio of 1 (same pinion and gear) were studied. A combination of numerical and experimental methods was used to obtain the best insight into the gear meshing process. Simulations of the gear meshing process were performed using a verified finite element analysis model. Torques of 0.8 Nm and 1.0 Nm were applied and gear meshing was simulated at center distances of 20.00 mm, 20.05 mm, and 20.10 mm. It was found that, as the center distance increased, the contact ratio decreased, which consequently leads to an increase in tooth root stress. Experimental gears tests were additionally conducted on a dedicated gear testing machine. The gears were tested under the same conditions previously simulated using the FEM model. Steel/PA6 gear pairs were tested, with at least three test repetitions for each combination of load and center distance. A significant reduction in gear service life of more than 30% was identified for larger center distances, while no pronounced effects on operating temperature were observed.