A Model to Predict Pocketing Power Losses in Spiral Bevel Gears

2015 ◽  
Author(s):  
E. Erkilic ◽  
D. Talbot ◽  
A. Kahraman
Keyword(s):  
Power Losses ◽  
Spiral Bevel Gears ◽  
Gear Teeth ◽  
Bevel Gears ◽  
Gear Mesh ◽  
Simulation Procedure ◽  
Aerospace Applications ◽  
Face Width ◽  
Spiral Bevel ◽  
Lubrication Conditions

A computational methodology is proposed for prediction of power losses due to pocketing (pumping or squeezing) of oil at the mesh interface of spiral bevel gears. The model employs an existing cutting simulation procedure to define surface geometries of the gears through face-milling and face-hobbing processes. A novel hypoidal discretization method is proposed to define pocket volumes between meshing gear teeth along circumferential and face width directions. An existing fluid mechanics formulation, utilizing principles of conservation of mass, momentum and energy, is used to compute the load-independent (spin) power losses due to pocketing of the medium in the gear mesh interface. A simulation of aerospace applications is presented to highlight the effects of lubrication conditions, on pocketing power losses.

scholarly journals Contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions

Friction ◽  
2021 ◽  
Author(s):  
Zongzheng Wang ◽  
Wei Pu ◽  
Xin Pei ◽  
Wei Cao
Keyword(s):  
Contact Stiffness ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Spiral Bevel Gears ◽  
Bevel Gears ◽  
Dry Contact ◽  
Spiral Bevel ◽  
Stiffness And Damping ◽  
Lubrication Conditions ◽  
Film Lubrication

AbstractExisting studies primarily focus on stiffness and damping under full-film lubrication or dry contact conditions. However, most lubricated transmission components operate in the mixed lubrication region, indicating that both the asperity contact and film lubrication exist on the rubbing surfaces. Herein, a novel method is proposed to evaluate the time-varying contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions. This method is sufficiently robust for addressing any mixed lubrication state regardless of the severity of the asperity contact. Based on this method, the transient mixed contact stiffness and damping of spiral bevel gears are investigated systematically. The results show a significant difference between the transient mixed contact stiffness and damping and the results from Hertz (dry) contact. In addition, the roughness significantly changes the contact stiffness and damping, indicating the importance of film lubrication and asperity contact. The transient mixed contact stiffness and damping change significantly along the meshing path from an engaging-in to an engaging-out point, and both of them are affected by the applied torque and rotational speed. In addition, the middle contact path is recommended because of its comprehensive high stiffness and damping, which maintained the stability of spiral bevel gear transmission.

Optimal Tooth Modifications in Face-Hobbed Spiral Bevel Gears to Reduce the Influence of Misalignments on Elastohydrodynamic Lubrication

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Vilmos V. Simon
Keyword(s):  
Carrying Capacity ◽  
Optimization Procedure ◽  
Load Carrying Capacity ◽  
Power Losses ◽  
Spiral Bevel Gears ◽  
Oil Film ◽  
Bevel Gears ◽  
Ehd Lubrication ◽  
Load Carrying ◽  
Spiral Bevel

In this study, an optimization methodology is proposed to systematically define the optimal tooth modifications introduced by head-cutter geometry and machine-tool settings to minimize the influence of misalignments on the elastohydrodynamic (EHD) lubrication characteristics in face-hobbed spiral bevel gears. The goal is to simultaneously maximize the EHD load-carrying capacity of the oil film and to minimize power losses in the oil film when different misalignments are inherent in the gear pair. The proposed optimization procedure relies heavily on the EHD lubrication analysis developed in this paper. The core algorithm of the proposed nonlinear programming procedure is based on a direct search method. Effectiveness of this optimization was demonstrated on a face-hobbed spiral bevel gear example. A drastic increase in the EHD load-carrying capacity of the oil film and a reduction in the power losses in the oil film were obtained.

Virtual Life and Performance Modeling of Aerospace Spiral Bevel Gears

2013 ◽  
Author(s):  
Eric C. Ames ◽  
Raja V. Pulikollu
Keyword(s):  
Gear Tooth ◽  
Drive Train ◽  
Test Facility ◽  
Load Spectrum ◽  
Mean Power ◽  
Spiral Bevel Gears ◽  
Bevel Gears ◽  
Gear Mesh ◽  
Rotor Drive ◽  
Spiral Bevel

Spiral bevel gears are widely used in the tail rotor drive trains of most rotorcraft. The loads associated with the tail rotor drive train are generally much more variable than those in the main rotor drive train primarily resulting from maneuvers. Over the life of any particular military rotorcraft it is not uncommon for the aircraft’s operating gross weight to steadily increase, causing the aircraft to fly at higher mean power levels and thus increasing the operating load spectrum associated with the tail rotor drive train. Special missions and equipment such as pulling a mine sweeping sled or very high altitude high gross weight assaults can put severe load demands on the tail drive train. This paper details an effort conducted to evaluate the effects of short to moderate duration overloads on the spiral bevel gears of the UH-60 helicopter tail rotor drive train. The focus of the effort was on the Tail Take-off gear mesh (TTO). An initial analytical assessment of the effect of loads above the endurance limit was conducted using an American Gear Manufacturers Association (AGMA) based approach. To confirm the validity of this approach, overload testing of the TTO gear mesh was conducted by the U.S. Army’s Aviation Applied Technology Directorate at the Navy’s test facility in Paxtuent River MD. Following the testing, the gear tooth bending and surface fatigue lives were analyzed using a microstructure based probabilistic tool developed by Sentient Corporation. The tool, known as Digital Clone was able to run hundreds of virtual tests that closely simulated the actual testing thus providing a low cost method for increasing the confidence associated with the effects of short to moderate high transient loads.

Load Distribution in Spiral Bevel Gears

2006 ◽  
Vol 129 (2) ◽  
pp. 201-209 ◽  
Author(s):  
Vilmos Simon
Keyword(s):  
Load Distribution ◽  
Point Contact ◽  
Design Data ◽  
Tooth Contact ◽  
Spiral Bevel Gears ◽  
Gear Teeth ◽  
Bevel Gears ◽  
Tooth Surfaces ◽  
Machine Theory ◽  
Spiral Bevel

A new approach for the computerized simulation of load distribution in mismatched spiral bevel gears with point contact is presented. The loaded tooth contact is treated in a special way: it is assumed that the point contact under load spreads over a surface along the “potential” contact line (Simon, 2006, Mech. and Machine Theory, in press), which line is made up of the points of the mating tooth surfaces in which the separations of these surfaces are minimal, instead of assuming the usually applied elliptical contact area. The bending and shearing deflections of gear teeth, the local contact deformations of mating surfaces, gear body bending and torsion, the deflections of supporting shafts, and the manufacturing and alignment errors of mating members are included. The tooth deflections of the pinion and gear teeth are calculated by the finite element method. As the equations governing the load sharing among the engaged tooth pairs and load distribution along the tooth face are nonlinear, an approximate and iterative technique is used to solve this system of equations. The method is implemented by a computer program. By using this program the load and tooth contact pressure distributions, the angular displacements of the driven gear and the stresses in the pinion and gear teeth are calculated. The influence of design data and transmitted torque on load distribution parameters and fillet stresses is investigated and discussed.

scholarly journals Experimental investigations and analysis on churning losses of splash lubricated spiral bevel gears

2017 ◽  
Vol 18 (4) ◽  
pp. 412 ◽  
Author(s):  
S. Laruelle ◽  
C. Fossier ◽  
C. Changenet ◽  
F. Ville ◽  
S. Koechlin
Keyword(s):  
Experimental Tests ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Spiral Bevel Gear ◽  
Power Losses ◽  
Test Rig ◽  
Specific Test ◽  
Spiral Bevel Gears ◽  
Bevel Gears ◽  
Spiral Bevel

Churning losses are a complex phenomenon which generates significant power losses when considering splash lubrication of gear units. However, only few works deal with bevel gears dipped lubrication losses. The objective of this study is to provide a wide variety of experimental tests on churning losses, especially getting interested in geometry of spiral bevel gears influence. A specific test rig was used in order to study a single spiral bevel gear partially immersed in an oil bath. Experiments have been conducted for several operating conditions in terms of speeds, lubricants, temperatures and gear geometries to study their impact on splash lubrication power losses. These experimental results are compared with the predictions from various literature sources. As the results did not agree well with the predictions for all operating conditions, an extended equation derived from previous works is introduced to estimate churning losses of bevel gears.

The Scuffing Resistance of WC/C Coated Spiral Bevel Gears

2014 ◽  
Vol 604 ◽  
pp. 36-40 ◽  
Author(s):  
Remigiusz Michalczewski ◽  
Marek Kalbarczyk ◽  
Waldemar Tuszynski ◽  
Marian Szczerek
Keyword(s):  
Bevel Gear ◽  
Spiral Bevel Gear ◽  
Test Rig ◽  
Low Friction ◽  
Spiral Bevel Gears ◽  
Gear Teeth ◽  
Bevel Gears ◽  
Trade Name ◽  
Gear Oil ◽  
Spiral Bevel

One of the main problems with the operation of spiral bevel gears is related to very severe conditions in the contact of the meshing teeth; therefore, lubrication is very difficult, which increases the risk of scuffing occurrence. One of the ways to achieve better scuffing resistance is by the deposition of a low-friction coating on the bevel gears teeth. Gear scuffing tests were performed using a bevel gear test rig designed and manufactured at ITeE-PIB. The authorial bevel gear scuffing test was performed. Specially designed, spiral bevel gears were used for testing. Two material combinations were tested: uncoated pinion - coated wheel and, for reference, both gears without coatings. The a-C:H:W (trade name WC/C) coating of DLC type was deposited on the wheel teeth. A mineral, automotive gear oil of API GL-5 performance level was used for lubrication. It is shown that the resistance to scuffing may be significantly improved when the a-C:H:W coating is deposited on the spiral bevel gear teeth.

Analytical Determination of Basic Machine-Tool Settings for Generation of Spiral Bevel Gears From Blank Data

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
Ignacio Gonzalez-Perez ◽  
Alfonso Fuentes ◽  
Kenichi Hayasaka
Keyword(s):  
Machine Tool ◽  
Analytical Determination ◽  
Local Synthesis ◽  
Spiral Bevel Gears ◽  
Bevel Gears ◽  
Face Width ◽  
The Face ◽  
Shaft Angle ◽  
Spiral Bevel

An approach for analytical determination of basic machine-tool settings for generation of spiral bevel gears from blank data is proposed. Generation by face-milling is considered. The analytical procedure is based on the similitudes between the conditions of generation between the gear member and its head-cutter and the conditions of imaginary meshing between the gear member and its crown gear. The blank data considered are the number of teeth of the pinion and the gear, the module, the spiral and pressure angles, the face width, the shaft angle, the depth factor, the clearance factor, and the mean addendum factor. These starting data can be established following the directions of the Standard ANSI/AGMA 2005-D03. Once the gear machine-tool settings are determined, an existing approach of local synthesis is applied to determine the pinion machine-tool settings that provide the desired conditions of meshing and contact of the gear drive. The developed theory is illustrated with a numerical example.

Minimization of the Influence of Misalignments on EHD Lubrication in Face-Hobbed Spiral Bevel Gears

2013 ◽  
Author(s):  
Vilmos V. Simon
Keyword(s):  
Carrying Capacity ◽  
Optimization Procedure ◽  
Load Carrying Capacity ◽  
Power Losses ◽  
Spiral Bevel Gears ◽  
Oil Film ◽  
Bevel Gears ◽  
Ehd Lubrication ◽  
Load Carrying ◽  
Spiral Bevel

In this study, an optimization methodology is proposed to systematically define optimal tooth modifications introduced by head-cutter geometry and machine tool settings to minimize the influence of misalignments on EHD lubrication characteristics in face-hobbed spiral bevel gears. The goal is to simultaneously maximize the EHD load carrying capacity of the oil film and to minimize power losses in the oil film when different misalignments are inherent in the gear pair. The proposed optimization procedure relies heavily on the EHD lubrication analysis developed by the author of this paper. The core algorithm of the proposed nonlinear programming procedure is based on a direct search method. Effectiveness of this optimization was demonstrated on a face-hobbed spiral bevel gear example. Drastic increase in the EHD load carrying capacity of the oil film and reduction in the power losses in the oil film were obtained.

scholarly journals Precision of Spiral-Bevel Gears

1983 ◽  
Vol 105 (3) ◽  
pp. 310-316 ◽  
Author(s):  
F. L. Litvin ◽  
R. N. Goldrich ◽  
J. J. Coy ◽  
E. V. Zaretsky
Keyword(s):  
Tooth Surface ◽  
Surface Geometry ◽  
Spiral Bevel Gears ◽  
Gear Teeth ◽  
Bevel Gears ◽  
Bearing Contact ◽  
Order Of Magnitude ◽  
Gear Trains ◽  
Spiral Bevel ◽  
Kinematic Errors

An analytical method was derived for determining the kinematic errors in spiral-bevel gear trains caused by the generation of nonconjugate surfaces, by axial displacements of the gear assembly, and by eccentricity of the assembled gears. Such errors are induced during manufacturing and assembly. Two mathematical models of spiral-bevel gears were included in the investigation. One model corresponded to the motion of the contact ellipse across the tooth surface (geometry I) and the other along the tooth surface (geometry II). The following results were obtained: 1) Kinematic errors induced by errors of manufacture may be minimized by applying special machine settings. The original error may be reduced by an order of magnitude. The procedure is most effective for geometry II gears. 2) When trying to adjust the bearing contact pattern between the gear teeth for geometry I gears, it is more desirable to shim the gear axially; for geometry II gears, shim the pinion axially. 3) The kinematic accuracy of spiral-bevel drives is most sensitive to eccentricities of the gear and less sensitive to eccentricities of the pinion. The pecision of mounting accuracy and manufacture is most crucial for the gear, and less so for the pinion.

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