AGMA 05FTM06-2005 pdf free.A Model to Predict Friction Losses of Hypoid Gears.
Efficiency losses in a gearbox are originated from several sources including gear mesh sliding and rolling friction, windage, oil churning, and bearing friction [34). When gears are loaded, a gear contact under load experiences combined sliding and rolling, both of which result in frictional losses. The amount of sliding frictional loss is directly related to the coefficient of friction, normal tooth load and relative sliding velocity of the surfaces while the rolling friction occurs due to the deformation of the two contacting surfaces. When the contact is lubncated, rolling ffictional losses are originated from the formation of the EHL film [35). Efficiency can be improved by reducing the coefficient of friction via precision manufacturing and srrioothening the contact surfaces and enhancement of lubricant properties. Existing approaches of improving efficiency are based mostly on experimental trial- and-error type procedures focusing on such parameters, while the predictive capabilities have been limited.
The main objective of this study is to develop a mechanical efficiency model for hypoid gears. The model allows an analysis of both face-hobbed and face-milled hypoid gears. The efficiency model will allow two methods of calculating p. i.e. published empincal formulae and a thermal EHL formulation. The differences amongst these approaches will be described, Parametric studies will be performed to investigate the influence of several relevant parameters such as speed, load, surface roughness. lubricant temperature as well as the assembly errors on the mechanical efficiency of hypoid gears. This study is focused primarily on the mechanical efficiency losses related to tooth friction, including sliding and rolling friction, while it relies on the published studies in terms of losses associated with windage, oil churning and bearings [34,35,64-69) when necessary.
2 Efficiency Model
2.1 Technical Approach
Figure 1 illustrates a flowchart of the efficiency computation methodology used in this study. Three main components are the gear contact analysis model, the friction coefficient computation model, and the gear pair mechanical efficiency computation formulation. The same methodology was applied by these authors earlier to spur and helical gears successfully [70J. It was also shown the parallel-axis efficiency model compares well with the gear pair efficiency experiments [77J. The gear contact analysis model uses the gear design parameters, operating conditions and errors associated with assembly. mounting and manufacturing of the tooth profile to predict load and contact pressure distributions at every contact point during each mesh position. Predicted load distribution or contact empirical formulae and a thermal EHL formulation.
The differences amongst these approaches will be described. Parametric studies will be performed to investigate the influence of several relevant parameters such as speed, load, surface roughness,lubricant temperature as well as the assembly errors on the mechanical efficiency of hypoid gears. This study is focused primarily on the mechanical efficiency losses related to tooth friction, including sliding and rlling friction, while it relies on the published studies in terms of losses associated with windage, oil churning and bearings [34,35,64-69] when necessary.AGMA 05FTM06 pdf free download.