An extremely wide selection of different plastic materials is currently available on the market. A major limitation, however, is a huge gap in gear-specific material data on these materials, which is a problem that has been persisting for decades now. Providing a step towards a solution is the German guideline VDI 2736, which proposes design rating methods (Ref. 2) along with testing procedures (Ref. 3) to be followed to generate reliable data required in the gear rating process. This paper delves into the current state of the art in plastic gear testing, providing a comprehensive overview of employed testing methods, supplemented with case studies.
For wind turbine main gearboxes (MGBs) with about 1 MW or higher power, gearbox designs with multiple power paths are used. They handle several mega-Newton-meter of torque economically. Earlier wind turbines with lower power ratings used parallel shaft gearboxes with only one power path but soon they were superseded by planetary gearboxes having typically three to five planets per stage. This paper describes experiences using planetary gears where “Flexpins” are used to improve the load sharing between the individual planets—representing the multitude of power paths—and along the planet’s face width.
This paper shows a methodology to extensively evaluate different designs of epicyclic gear systems. As outlined, no choice is required on the part of the designer who is free to probe all design variables.
This report investigates the wear morphology on the large end of tapered rollers and the inner ring's large end rib on a planet carrier TRB from a multi-megawatt wind turbine gearbox. The literature on abrasive wear has many classifications, including 2-body abrasion, 3-body abrasion, scratches, grooving abrasion, rolling abrasion, cutting abrasion, and plowing abrasion. For this analysis, we have selected grooving abrasion, a common problem in wind turbine gearboxes and a prominent failure mode on many bearings, particularly planetary carrier bearings and planet bearings. Grooving abrasion is frequently observed on cylindrical roller bearings (CRB) and tapered roller bearings (TRB). Fitzsimmons and Clevenger conducted tests on roller end/rib wear for TRBs with contaminated gear oil, and they provided an excellent explanation of the mechanism.
This paper presented some steps to get more insight into the effect of meshing damping on the dynamic response and noise emission of a two-stage gearbox transmission system. For this purpose, two variants of the model with different gear materials, one with plastic gears and one with steel gears, were considered. Both variants were designed for the same number of cycles of operation with similar root and flank safeties. The forced response analysis of the models was carried out and the exciting reaction bearing forces were calculated to evaluate which model can achieve better NVH characteristics results with lower noise emission from the housing.
Tactile or contact probes are the most common metrology technique in the coordinate measurement world, including the more specialized gear measurement community. Tactile probes can be active or passive, scanning or touch only, and may vary in cost and performance depending on the system itself. They are offered by multiple industrial companies as standalone OEM products (e.g., Renishaw) or only included in their coordinate measuring machines (e.g., Zeiss, Klingelnberg, and Hexagon). Their overall performance, especially their robustness and flexibility, have led to a gold standard for most metrology tasks.
Gear skiving is used for both soft and hard finishing. As a quality critical final step in hard finishing, the process can be used to create modifications to the tooth flank. At present there is no knowledge of the extent to which topological modifications can be applied by gear skiving. In this report, the feasibility of manufacturing topological modifications on an external gear through adapted kinematics for gear skiving has been investigated.
As the challenges in bevel and hypoid gear manufacturing need to be addressed, the objective of this paper is to show the tool and process design can be optimized based on the results of the manufacturing simulation BevelCut.
The main objective of this study is to perform an experimental evaluation of the structural model of a five-planet first planetary stage from a modern 6MW wind turbine gearbox.