A calculation method of sliding friction coefficient on tooth surface for helical gear pair based on loaded tooth contact analysis and elastohydrodynamic lubrication theory

2020 ◽  
pp. 135065012096689
Author(s):  
Cheng Wang ◽  
Mao Ken
Keyword(s):  
Friction Coefficient ◽  
Sliding Friction ◽  
Elastohydrodynamic Lubrication ◽  
Helical Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Tooth Contact Analysis ◽  
Sliding Friction Coefficient ◽  
Loaded Tooth Contact Analysis ◽  
Helical Gear Pair

The sliding friction coefficient on tooth surface is related to power loss, carry capacity and transmission performance of gear. Reasonable transmission analysis of gear pair is the premise of accurate calculation of sliding friction coefficient on tooth surface. However, for helical gear pair, the line contact without considering machining error/installation error/modification of gear is usually adopted to replace the major axis of ellipse caused by contact load. Therefore, in this paper, contact path on tooth surface, length of contact line, load distribution on tooth surface and loaded transmission errors are accurately calculated by loaded tooth contact analysis (LTCA). Combing with elastohydrodynamic lubrication (EHL) theory, a calculation method of sliding friction coefficient on tooth surface for helical gear pair is proposed.

Dynamic model of a helical gear pair considering tooth surface friction

2020 ◽  
Vol 26 (15-16) ◽  
pp. 1356-1366 ◽  
Author(s):  
Cheng Wang
Keyword(s):  
Friction Coefficient ◽  
Dynamic Model ◽  
Sliding Friction ◽  
Surface Friction ◽  
Helical Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Tooth Contact Analysis ◽  
Sliding Friction Coefficient ◽  
Helical Gear Pair

The tooth surface friction is one of the main sources of gear vibration and noise. The current challenging problems in research of a helical gear pair dynamics considering tooth surface friction include the following: (1) Calculation accuracy of the tooth surface friction factor needs to be improved. (2) The meshing process of a helical gear pair has not been fully taken into account in a dynamic model. To solve these problems, a dynamic model of a helical gear pair considering tooth surface friction is proposed in this article. First, based on the tooth contact analysis and loaded tooth contact analysis of a helical gear pair, excitation of time-varying meshing stiffness, the sliding friction coefficient on tooth surface, and the arm of friction force are preliminarily calculated. Second, the dynamic model of a helical gear pair considering tooth surface friction is built and solved, in which the dynamic meshing force/speed/displacement is calculated. The sliding friction coefficient on tooth surface, arm of friction force, and dynamic equations form a coupled system. By decoupling calculation, the model system equations are solved. Finally, an example is presented to verify the proposed model.

Research on Dynamic Model of Double Helical Gear Pair Based on TCA and LTCA

2019 ◽  
Vol 24 (3) ◽  
pp. 476-484 ◽  
Author(s):  
Cheng Wang ◽  
Shouren Wang ◽  
Gaoqi Wang
Keyword(s):  
Friction Coefficient ◽  
Dynamic Model ◽  
Dynamic Models ◽  
Sliding Friction ◽  
Helical Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Axial Vibration ◽  
Sliding Friction Coefficient ◽  
Helical Gear Pair

Numerous dynamic models of spur gears, helical gears, bevel gears, and face gears can be found in various studies. However, studies that focus on the dynamic model of a double helical gear pair are quite limited. The author proposed a model of a double helical gear pair by only considering the axial vibration. The author did not consider the friction and multiple backlashes in the proposed model. The friction force of the tooth surface and backlash are important factors that can cause complex non-linear phenomena in gear pairs. Therefore, a dynamic model of a double helical gear pair that takes into consideration the axial vibration, friction and multiple backlashes is proposed. Firstly, based on the tooth contact analysis (TCA) of a double helical gear pair, the path of contact and meshing time from engagement to disengagement are obtained. The formula for determining the sliding friction coefficient is introduced. Based on TCA and the dynamic meshing force provided by the subsequent dynamics model of double helical gear pair, the sliding friction coefficient of the tooth surface is calculated. Secondly, the stiffness excitation, gear-into impact excitation and error excitation (including the axial displacement caused by the errors of manufacture and installation under low speed) are calculated according to the existing research results. Following this, a dynamic model of a double helical gear pair that takes into consideration the axial vibration, friction and multiple backlashes is both built and solved. Finally, an example is presented to verify the corresponding results.

Using variable modulus to modify a rack cutter and generate a gear pair

2022 ◽  
pp. 095440622110617
Author(s):  
Yang Hsueh-Cheng ◽  
Zhong-Wei Huang
Keyword(s):  
Helical Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Tooth Contact Analysis ◽  
Parabolic Profile ◽  
Face Width ◽  
Variable Modulus ◽  
The Face ◽  
Helical Gear Pair ◽  
Assembly Error

In this paper, two normal imaginary helical rack cutters were first established. One of these cutters is a skewed-rack cutter with an asymmetrical straight edge. The other is a rack cutter with an asymmetric parabolic profile. Second, the gear’s tooth surface of the asymmetric parabolic rack cutter is modified to be barrel-shaped based on a variable modulus. The tooth thickness of the gear is gradually reduced along the face width of the tooth from the middle of the tooth surface. Then the coordinate relationship between the gears’ blanks and the imaginary helical rack cutters was established. Through the differential geometry, crowned and uncrowned helical gear pairs were generated. Because of human factors, when the gear pair is installed, it is easy to cause the gear pair edge contact. It is necessary to add artificial assembly error settings through the tooth contact analysis to investigate the kinematic errors and contact conditions of the crowned and uncrowned helical gear pair. The mathematical models and analysis methods proposed for the crowned imaginary rack cutter using variable modulus should be useful for the design and production of double crowned helical gears with asymmetric parabolic teeth.

Parametric Studies of Mechanical Power Loss for Helical Gear Pair Using a Thermal Elastohydrodynamic Lubrication Model

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Mingyong Liu ◽  
Peidong Xu ◽  
Chunai Yan
Keyword(s):  
Friction Coefficient ◽  
Thermal Effect ◽  
Power Loss ◽  
Elastohydrodynamic Lubrication ◽  
Mechanical Efficiency ◽  
Helical Gear ◽  
Tribological Performance ◽  
Mechanical Power ◽  
Gear Pair ◽  
Helical Gear Pair

In this study, a comprehensive mechanical efficiency model based on the thermal elastohydrodynamic lubrication (TEHL) is developed for a helical gear pair. The tribological performance of the helical gear pair is evaluated in terms of the average film thickness, friction coefficient, mechanical power loss, mechanical efficiency, etc. The influence of basic design parameters, working conditions, thermal effect, and surface roughness are studied under various transmission ratios. Results show that the contribution of thermal effect on the tribological performance is remarkable. Meanwhile, the rolling power loss constitutes an important portion of the total mechanical power loss, especially around the meshing position where the pitch point is located in the middle of contact line and the full elastohydrodynamic lubrication (EHL) state with the friction coefficient less than 0.005. The proper increase of normal pressure angle and number of tooth can improve the tribological performance. The influence of helix angle on the mechanical efficiency is less significant. A positive addendum modification coefficient for pinion and a negative addendum modification coefficient for wheel are good for improving the mechanical efficiency. The results provide the tribological guidance for design of a helical gear pair in engineering.

Vibration-based fault diagnosis of helical gear pair with tooth surface wear considering time-varying friction coefficient under mixed EHL condition

2021 ◽  
pp. 1-16
Author(s):  
Siyu Wang ◽  
Rupeng Zhu
Keyword(s):  
Dynamic Response ◽  
Hydrodynamic Lubrication ◽  
Helical Gear ◽  
Calculation Model ◽  
Tooth Surface ◽  
Time Varying ◽  
Gear Pair ◽  
Surface Wear ◽  
Mesh Stiffness ◽  
Helical Gear Pair

Abstract Based on “slice method”, the improved time-varying mesh stiffness (TVMS) calculation model of helical gear pair with tooth surface wear is proposed, in which the effect of friction force that obtained under mixed elasto-hydrodynamic lubrication (EHL) is considered in the model. Based on the improved TVMS calculation model, the dynamic model of helical gear system is established, then the influence of tooth wear parameters on the dynamic response is studied. The results illustrate that the varying reduction extents of mesh stiffness along tooth profile under tooth surface wear, in addition, the dynamic response in time-domain and frequency-domain present significant decline in amplitude under deteriorating wear condition.

Tool Profile Modification of Hypoid Gear Machined by Duplex Helical Method

2021 ◽  
Author(s):  
Shunxing Wu ◽  
Hongzhi Yan ◽  
Zhiyong Wang ◽  
Rengui Bi ◽  
Jia Li
Keyword(s):  
Geometric Model ◽  
Tooth Surface ◽  
Gear Pair ◽  
Hypoid Gear ◽  
Tooth Contact Analysis ◽  
Edge Contact ◽  
Profile Modification ◽  
Tool Profile ◽  
Tooth Surfaces ◽  
Loaded Tooth Contact Analysis

Abstract For the hypoid gear pair of the heavy-duty vehicle drive axle machined by the duplex helical method, in order to avoid edge contact and stress concentration on the tooth surface, a four-segment tool profile is designed to modify the concave and convex surfaces simultaneously. First, the geometric model of the four-segment tool profile is established. Second, the mathematical model of the duplex helical method based on the four-segment tool profile is established, and the method of solving the tooth surface generated by the connecting points of the four-segment tool profile is given. Finally, the finite element method of loaded tooth contact analysis is used to analyze the meshing performance of the gear pair obtained by the four-segment tool profile modification, and the results are compared with the original gear pair. The results show that after the tooth surfaces are modified, the edge contact of the tooth surfaces are avoided, the stress distribution of the tooth surfaces are improved, the maximum contact stress of the tooth surfaces are reduced, and the fatigue and wear life of the tooth surface are improved.

Sign in / Sign up

Export Citation Format

Share Document