Analysis of elastohydrodynamic lubrication of steel planar wormgear drive

Based on study of elastohydrodynamic lubrication (EHD) and meshing theory of planar worm gear drive, EHD model for the drive is proposed. Minimum film thickness on the whole contact area is calculated. EHD status for the drive is analyzed. The distributions of film thickness show that, EHD status during entry engagement is better than that during exit engagement, and EHD status of worm addendum area is better than that of dedendum area. Influencing factors such as work conditions and optimized parameters along with their effects were analyzed. Theoretical analysis suggests that the optimizing pressure angle and increasing worm pitch diameter have influence on improving lubricant performance of the planar worm gear drive.     

THEORETICAL INVESTIGATION AND PARAMETER OPTIMIZATION ON ROLLING CONE ENVELOPING HOURGLASS WORM GEARING

In this paper, a new high - strength worm gearing, named'rolling cone enveloping hourglass worm gearing' is proposed. With such a new type of worm gearing, the motion form between meshing tooth surfaces is changed in nature. A systematic theoretical study. a lot of numerical calculations and parameter analyses have been done. Based on these analyses,the optimum design of worm gearing is obtained. It is shown that this worm gearing possesses the virtues of high efficiency, large load capacity, long life -span and easy meanufacture.     

The Research on Stiffness of Double Involute Gear with Ladder shape Teeth

The stiffness of the tooth with different profile parameters,meshing stiffness and the coefficients of loading distribution allowing for no error are calculated and analyzed on double involute gear with ladder shape teeth for the first time,and the results are made comparison with traditional involute gear;The stiffness of the double involute gear and the meshing stiffness are both increased,and the coefficients of loading distribution are basically unchanged.The energy integration method is also put forth to solve stiffness approximately by linear approximating the tooth profile curve.     

The Experimental Study of Lubrication Mechanism of Double Enveloping Hourglass Worm Gearing

According to the characteristic of contact and lubrication of double enveloping hourglass worm gearing,a simplified contact model that can simulate the lubrication mechanism of coupling effect of squeezing effect and entraining effect of this worm gearing is presented.A simulating test set is designed.The lubrication mechanism of coupling effect of squeezing effect and entraining effect is studied experimently by using this set.And the influences of rotation speed,loading speed and depth of oil pocket on the forming of lubrication film and loading ability between contact surfaces are analyzed.Some beneficial conclusions are obtained.     

Bending Stress Analysis on Backlash Adjustable Worm Transmission

The full name of variable tooth thickness plane worm gear transmission is. Backlash adjustable plane worm gear with variable tooth thickness enveloping worm transmission, which is a new kind of accurate power transmission that is intervenient between traditional motion transmission and power transmission. Tooth surface equations of the variable tooth thickness plane worm gear transmission are deduced based on the theory of engagement. Basing on the result, the authors create a finite analysis model of backlash adjustable variable tooth thickness plane enveloping worm with perfect tooth shape by using I-DEAS software, and then has done finite element analysis of backlash adjustable variable tooth thickness plane enveloping worm transmission. Finally, the author drew a conclusion about distribution of principal stress and load distribution between teeth, which offer some references for strength and performance analysis of worm transmission.     

Force Analysis on Meshing Surface and Stress Research of the Cone Roller Enveloping Worm Gearing Transmission

By using the finite element elastic contact analysis method combined with the I-DEAS engineering analysis software, this paper studies the strength of the cone roller enveloping worm gearing,which is a new type of worm gearing transmission,on SUN-4 working station. It also analyzes loading distribution among meshing gears, the contact force distribution along the contact line ,the bending stress distribution and the contact stress distribution of the cone roller enveloping worm gearing with three-tooth meshing instantaneously. Besides,it provides the theoretic basis in the further researches for the new type of worm gearing transmission.     

Contact analysis of a new style planetary reducer with a double crank and internal gear board

To address the problems of low carrying capacity and short life of bearings in current ring reducers, a new type of ring reducer is proposed which consists of a two stepped transmission. One is a planetary transmission, and the other is an N type planetary transmission with a low tooth number difference. Based on the analysis of structural features, the transmission principle, and a transmission load situation, a contact finite element model of the new type of ring reducer is set up, and the stress value and the actual pairs of meshing teeth are derived by calculation. Based on gear modification research theory, the second stage transmission gear pairs of the new reducer are modified on its teeth profiles. Results demonstrate that the load capacity of transmission gear pairs have been enhanced greatly.     

DEVELOPMENT AND TEST ON ROLLING CONE ENVELOPING HOURGLASS WORM PAIR

The rolling cone enveloping hourglass worm pair has been successfully developed, in which there is almost only rolling friction between the meshing tooth surfaces, and both the worm and wormwheel have hard surfaces. Such a new type of hourglass worm pair is particularly-favorable for power transmission. This paper presents the design. manufacting and testing of this worm pair.     

Coupled Thermo-Elastic Contact Finite Element Method and It''s Application in Gearing

A new finite element method is presented in this paper to analyze the thermo- elastic contact problem with heat input on meshing tooth faces. The computational model of meshing gear has been established and the frictional heat input on meshing tooth faces is estimated. In addition, 2-D finite element analysis program for this kind of problem is listed. The test and practical examples are given to show the validity and versatility of this method.     

THEORETICAL INVESTIGATION OF SPHERE RE-ENVELOPING HOURGLASS WORM GEARING

On the condition of avoiding the"undercutting,"and "sharpening" of worm tooth, it is now regarded as an important subject in the field of meshing principle studying of the "multiple-thread small reducation ratio" hourglass worm gearing with developable tooth surfaces to reduce the gorge pitch circle diameter of worm, raise meshing efficiency and strength of the wheel tooth and improve the unresonable structure of the pair. In this paper, a new type of hourglass worm gearing with developable tooth surfaces -"Sphere Re-nveloping Hourglass Worm Gearing" is studied. It shows that 4a satisfied result to above subject can be obtained if this worm gearing is applied.     

Research on analysis of force and contacting stress for the discrete teeth harmonic drives

Mechanical analysis for the discrete teeth harmonic drive gear pair is carried out. The force on discrete teeth is calculated based on the deformation coordination equation,and the contact stress of meshing pair is obtained by Hertz equation. According to transmission periodicity of the discrete gear harmonic wave and the input angle values of continuous sampling wave generator,the distribution of discrete teeth harmonic drive meshing force and contract stress in rigid tooth profile,tooth wave generator and discrete teeth is obtained. By studying the top cutting phenomena in rigid tooth profiles,the change trend of meshing force and contact stress on the contact surface is found,and positions for high meshing force and high contact stress in transmission are also found,in order to provide reference for further intensity and structure optimization design.     

Analysis on Oylindrical Worm in Traction Machine and Modifications

Cone enveloping cylindrical worm in traction machine as instance, theoretical analysis on cylindrical worm transmission has been theoretically analyzed, and efficiency test and load capability test of traction machine with YJ240 cylindrical worm have been done on open power gear experimental instrument. According to the experimental data, it indicates cylindrical worm have some weaknesses on load capability, efficiency, adjustment possibility of tooth backlash and so on. Therefore, on purpose of improving integral performance of traction machine, face worm with variable tooth thickness may be used as primary drive mechanism in traction machine instead of cylindrical worm.     

Transmission model of higher-order elliptical bevel gearing and motion simulation for interference checking

Higher-order elliptical bevel gear is a typical form of the noncircular bevel gear transmission.Space spherical coordinate system of the bevel gear meshing is set up based on the meshing theory of space transmission.The varying relationship among the pitch curve,tooth profile and mesh lines are analyzed,and the equation of the gear tooth surface is developed with matrix method based on space coordinate transformation.The basic parameters of the noncircular bevel gear such as transmission ratio,modulus and the number of teeth are designed,and detailed analysis of the influence of the eccentricity on the relevant parameters is carried out as well.By using discrete numerical method and three-dimensional software,the mathematical model of the tooth profile and virtual physical model of the noncircular bevel gear are established,and then simulation on its motion and interference checking are performed.Finally,the approach for design,calculation and generation of the tooth profile is obtained and its correction has been verified by experiment.     

A Solid Modeling and Geometric Analysis of Hourglass Worm Gearing

Based on the theory of conjugate surface and computer graphics, a solid modeling method of hourglass worm gearing is presented. Assembly simulation of worm gearing is carried out, clearance and interference between meshing tooth surfaces are analyzed, and effects of machining and modification of assembling parameters on meshing and contact between tooth surfaces are investigated.     

Worm wheel grinding method of convex pitch line non-circular gear

To overcome the precision machining difficulty of non-circular gear, a convex pitch curve of non-circular gear and worm grinding method is presented. Firstly, worm wheel is reduced to rack cutter and a rack machining convex pitch curves of non-circular gears sport model is set up. Then based on the structure of CNC worm wheel grinding machine tools and machining principle, electronic gear box of machine tools is designed and active and following axes are planned. At the mean time, the synchronous coefficient of machine tools between synchronization is deduced by machining principle of equal arc-length, and interaction models of grinding are established. At last, the worm wheel manual presetting cutter methods with non-circular gear are given and worm grinding wheel mounting angle, axial position and axial location parameter can be adjusted along the gear.     

Effects of time-varying friction coefficient on hypoid gear dynamics

This paper develops a generalized 3-dimensional 14-DOF dynamic model for hypoid gear which considers the time-varying friction coefficient and lubrication situation. We propose a mixed elastohydrodynamic lubrication(EHL) friction model of hypoid gear tooth contact to reflect the realistic lubricant situation in gear transmission system consisted of full film contact and asperity contact. Under the mixed lubrication condition, the effects of time-varying friction coefficient on gear dynamic is analyzed. The load sharing coefficient is used to calculate the instantaneous friction coefficient at each contact point along the contact path. Friction coefficient model based on mixed elastohydrodynamic lubrication(Mixed EHL) is incorporated into the dynamic model to predict the dynamic mesh force and transmission error with constant and time-varying friction coefficient. The simulation results under a wide range of speed and load show that the time-varying friction coefficient has a marginal effect on the dynamic response.     

Gear-bearing coupling dynamics characteristics of wind turbine planetary gear transmission system under variable load

Considering that the transmission system of wind turbine works in complex and changing load environment caused by stochastic wind speed,this paper uses sparse least squares support vector machine(SL-SVM) to simulate wind speed of true wind field,and obtains time-varying wind load caused by stochastic wind speed. The lumped-parameter method is used to develop a dynamic model of planetary gear transmission system of wind turbine coupled with bearing. The model includes the varying wind load,time-vary mesh stiffness of gear pair and time-vary stiffness of rolling element bearing. The numerical method is used to simulate the dynamic performance of planetary gear system of Multibrid Technology Wind Turbine with 1.5 MW rated power. The vibration displacement responses of the transmission system are obtained as well as dynamic meshing force each pair of gear and nonlinear bearing forces. The research can provide a foundation for optimizing dynamic performance and reliable design of gear transmission system of wind generator.     

Intensity Comparative Analysis Based on Ideas Between Involute Gear and Double Involute Gear

Modeler and simulation modules in Ideas software are used to build the finite element models on involute gear and double involute gear with accurate tooth shape, and with the same design parameters and under the same loads, finite element contact analysis has been done. At last, the contact stress and bending stress on the two types gear transmission at the different meshing positions are solved out, and comparative analysis and study have been done. At the same time, that the ladder-shape tooth on the double involute gear how to influence contact stress and bending stress is emphatically analysed. All above offer the theoretical foundation that bring the double involute gear with ladder-shape tooth into the industry.     

Fine Microstructure of Novel Microdistortion Gear Steel

In order to reduce quench deformed of car gear, a new kind of microdistortion gear steel is developed and its fine microstructure is discussed by SEM. The results show that the tested steel can obtain carbide free bainitic ferritic laths with fine microstructure under air-cooling condition. The bainitic ferritic laths, sublaths and subunits are surrounded by retained austenite, which can insure the gear steel possesses high strength and toughness, the impact toughness has increased remarkably. The good mechanical performance of the steel can meet the service demands of the gear.     

PREDICTION OF QUATITIES CONTROL OF STRAIGHT BEVEL GEAR SHAPING

Based on the forming and meshing theories of gears, the relationship between machining parameters and driving quatity of straight bevel gears has been discussed. The forming and meshing processes have been simulated with a microcomputer. The correctness of the theoretical analysis and calculation has been proved by shaping experiment.