Determination of the Tooth Surface Friction Coefficient of a Pair of Mating Gears Based on the Distribution Along the Tooth Profile Precisely Measured With the Gravity Pendulum Method

2000 ◽  
Author(s):  
Kohei Hori ◽  
Iwao Hayashi ◽  
Nobuyuki Iwatsuki
Keyword(s):  
Friction Coefficient ◽  
Oscillation Amplitude ◽  
Surface Friction ◽  
Small Region ◽  
Tooth Profile ◽  
Tooth Surface ◽  
Gear Pair ◽  
Friction Coefficients ◽  
Mean Values ◽  
Tooth Surfaces

Abstract A new gravity pendulum method has been proposed in order to precisely measure the tooth surface friction coefficient of a pair of mating gears excluding the bearing loss. In this method, one of the mating gears, which is fixed on a gravity pendulum, is put on the other gear, which is fixed on the ground, and is freely oscillated. The center-to-center distance between the mating gears is kept constant with a flexure hinge mechanism in order to accurately reproduce the relative motion, including rolling and sliding, between the tooth surfaces of practical rotating gears. This method has a great advantage, in that the tooth surface friction co-efficient can be measured in a very small region of the tooth profile, because the initial oscillation amplitude can be set approximately one arc-degree. The distribution of the friction coefficients along the tooth surface has been precisely measured for the exact one pair-, inexact one pair-, and two pair-tooth engagements of an internal gear pair and an external gear pair. Also, the mean values of the distributed tooth surface friction coefficients are calculated by taking the specific sliding between the tooth surfaces into account, and are compared with each other.

scholarly journals Meshing principle analysis of 3-DOF involute spherical gear

2020 ◽  
Vol 213 ◽  
pp. 02029
Author(s):  
Baichao Wang ◽  
Xue Zhang ◽  
Litong Zhang ◽  
Xianting Lu
Keyword(s):  
Mathematical Model ◽  
Tooth Profile ◽  
Bevel Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Tooth Surfaces ◽  
Three Degree Of Freedom ◽  
Relationship Of ◽  
The Mathematical Model ◽  
Spherical Gear

In this paper, a mathematical model of meshing motion of three degree of freedom involute spherical gear pair is constructed. The mathematical model can realize continuous meshing transmission between gear pairs without transmission principle error. Based on the meshing principle and motion analysis of the gear, the tooth profile of the spherical gear is designed by combining the two tooth surfaces of the involute ring gear and the hemispherical bevel gear. According to the conjugate motion relationship of spherical gear pair, a mathematical model of arc tooth surface of hemispherical bevel gear is established, and the mathematical description of the tooth profile of spherical gear is completed by combining the equation of ring tooth surface. It provides the basis and Reference for the meshing design of ball gear.

scholarly journals A Novel Approach to Calculating the Transmission Accuracy of a Cycloid-Pin Gear Pair Based on Error Tooth Surfaces

2021 ◽  
Vol 11 (18) ◽  
pp. 8671
Author(s):  
Chang Liu ◽  
Wankai Shi ◽  
Lang Xu ◽  
Kun Liu
Keyword(s):  
Transmission Error ◽  
Tooth Profile ◽  
Tolerance Allocation ◽  
Tooth Surface ◽  
Gear Pair ◽  
Eccentric Load ◽  
Novel Approach ◽  
Manufacturing Errors ◽  
Tooth Surfaces ◽  
Theoretical Analyses

Transmission error (TE) and backlash are important parameters used to evaluate the transmission accuracy of cycloid-pin drives. Existing calculation methods are mostly based on two-dimensional tooth profile models, and these methods ignore the influence of some abnormal meshing phenomena caused by profile modifications (PMs), manufacturing errors (MEs), and assembly errors (AEs), such as the instantaneous mesh-apart of tooth pairs and the eccentric load on the tooth surface. To fill this gap, a novel approach to accurately calculating the TE and backlash of a cycloid-pin gear pair based on the error tooth surfaces is proposed, and its feasibility and effectiveness are validated by comparison with the theoretical analyses and the results from the literature. Based on this, the effects of the PMs, MEs, and AEs on the transmission accuracy are studied, which will be helpful in optimizing the tooth profile design of a cycloid gear and the tolerance allocation during the installation of a gear pair. The proposed method is also expected to provide accurate error excitation data for the dynamic analysis of cycloid-pin drives.

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.

Study on the lubrication characteristics of spur gear pairs with low sliding ratio under mixed EHL

2021 ◽  
pp. 1-26
Author(s):  
Jiang Zhao ◽  
Wei Sheng ◽  
Zhengminqing Li ◽  
Hong Zhang ◽  
Rupeng Zhu
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Temperature Rise ◽  
Thickness Distribution ◽  
Tooth Profile ◽  
Tooth Surface ◽  
Spur Gears ◽  
Gear Pair ◽  
Line Contact ◽  
Lubrication Characteristics

Abstract The relative sliding at the meshing point directly affects the contact and lubrication characteristics of the gear pair, and is the main cause of gear wear and power loss. In this research, for investigation of a new type of low sliding ratio (LSR) gear pair whose tooth profile is constructed by a cubic function, a Three-dimensional (3D) mixed EHL line contact model was established with consideration of the effect of tooth profile geometry, transient motion characteristics, load distribution and machining roughness. The distribution of the center film thickness of the LSR gear along the meshing line was predicted through an example the result of which was compared with a typical line contact EHL formula to verify the model. In addition, the difference was investigated in film thickness distribution, of friction coefficient and temperature rise between LSR spur gears and involute spur gears. Basing on above, there was discussion about the effect of 3D rough tooth surface on the contact lubrication characteristics of LSR gears. The results demonstrated that the minimum center film thickness of the LSR gear appeared at the alternating point of the concave and convex tooth surfaces. At the same time, compared with the involute gear, the LSR gear significantly increased the film thickness at the start and ending points of the meshing, and reduced the friction coefficient and the flash temperature rise.

Estimation of Gear Friction Coefficient using Directional Parameter of Tooth Surface

2021 ◽  
pp. 1-27
Author(s):  
Junichi Hongu ◽  
Ryohei Horita ◽  
Takao Koide
Keyword(s):  
Friction Coefficient ◽  
Contact Surface ◽  
Gear Tooth ◽  
Correction Term ◽  
Tooth Surface ◽  
Oil Film ◽  
Tooth Surfaces ◽  
Frictional Coefficients ◽  
Finishing Processes ◽  
The Relationship

Abstract This study proposes a modification of the Matsumoto equation using a directional parameter of tooth surfaces to adapt various gear finishing processes. The directional parameters of a contact surface, which affect oil film formations, have been discussed in the field of tribology; but this effect has been undetermined on the meshing gear tooth surfaces having directional machining marks. Thus, this paper investigates the relationship between the gear frictional coefficients and the directional parameters (based on ISO25178) of their tooth surfaces with the various finishing processes; and modifies the Matsumoto equation by introducing a new directional parameter to augment the various gear finishing processes. Our findings indicate that through optimizing the coefficient of the correction term the include the new directional parameter, the calculated friction values using the modified Matsumoto equation correlate more highly to the experimental friction values than that using the unmodified Matsumoto equation.

scholarly journals Dynamic characteristics of the gear-rotor system in compressed air energy storage considering friction effects

2021 ◽  
Vol 12 (1) ◽  
pp. 677-688
Author(s):  
Xinran Wang ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xingjian Dai ◽  
Haisheng Chen
Keyword(s):  
Energy Storage ◽  
Friction Coefficient ◽  
Dynamic Characteristics ◽  
Surface Friction ◽  
Rotor System ◽  
Compressed Air ◽  
Contact Temperature ◽  
Tooth Surface ◽  
Compressed Air Energy Storage ◽  
Rotating Speed

Abstract. The tooth surface friction effects and the resulting tooth surface contact temperature are important factors for the dynamic characteristics of a gear-rotor system in compressed air energy storage (CAES). Therefore, a 3∘ of freedom finite-element model of the system is set up in which the lubrication state of the gear pair, tooth surface friction, contact temperature of the tooth surface, backlash and unbalanced excitation are considered. The friction coefficient is calculated according to the variation of the lubrication state, and the tooth surface contact temperature is derived based on the friction coefficient. The tooth profile deformation caused by the change in the contact temperature is calculated, and the resulting effects on backlash and comprehensive meshing stiffness are considered. The influence of rotating speed, torque load and viscosity of lubricating oil on the system response is studied, and the variation of the friction coefficient, flash temperature of the tooth surface, pressure of the tooth surface and so on are discussed in detail. The results indicate that when the friction coefficient is derived according to the variation of the lubrication state, the variation of the contact temperature of the tooth surface with rotating speed is quite different from that calculated based on a friction coefficient which is set artificially. This leads to a new variation of the dynamic response of the gear-rotor system, and the method of stabilizing the operation of the system is put forward based on the optimization curve for the operation of the system. The results obtained in this paper will provide a reference for the study and design of a gear-rotor system in CAES.

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.

scholarly journals Study on bifurcation characteristics of multi-clearance bending torsional coupling gear transmission based on EHL

2020 ◽  
Vol 12 (6) ◽  
pp. 168781402093750
Author(s):  
Hao Dong ◽  
Jianwen Zhang ◽  
Libang Wang
Keyword(s):  
Friction Coefficient ◽  
Periodic Motion ◽  
Chaotic Motion ◽  
Hydrodynamic Lubrication ◽  
Surface Friction ◽  
Tooth Surface ◽  
Time Varying ◽  
Mesh Stiffness ◽  
Vibration Model ◽  
Non Linear

In order to study the influence of tooth surface friction on the non-linear bifurcation characteristics of multi-clearance gear drive system, a 6 degree-of-freedom bending torsional coupled vibration model was established. The time-varying mesh stiffness, backlash, support clearance and damping were considered comprehensively in this non-linear vibration model. Loaded tooth contact analysis was used to calculate the time-varying mesh stiffness. Based on the elasto-hydrodynamic lubrication, the time-varying friction coefficient was calculated. Runge–Kutta numerical method was used to solve the dimensionless dynamic differential equation. Using phase diagram, Poincaré diagram, time history diagram, and spectrum diagram, the influence of tooth surface friction on bifurcation characteristics was studied. The results show that the system undergoes a change from 1-periodic motion, multi-periodic motion, to chaotic motion through bifurcation and catastrophe when the speed changes independently. When the friction coefficient of tooth surface changes from 0, 0.05 to 0.09, the chaotic motion of the system is suppressed. Similarly, with the increase in tooth friction, the chaotic motion characteristics are suppressed. Tooth surface friction is the main factor affecting chaotic motion. With the increase in friction coefficient of tooth surface, the chaos characteristic does not change obviously and the vibration amplitude decreases slightly.

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