CUTTING PARAMETERS DEFINITION FOR KINEMATIC OPTIMISATION OF SPIRAL BEVEL GEARS

The contact analysis of uniform tooth height epicyclical spiral bevel gears stemming from Klingelnberg´s Cyclo-Palloid System has an important role in preliminary design. The simultaneous generation of gear surfaces and contact simulation is the basis of the analysis. A numerical program for theoretical contact identification has been developed. Longitudinal settings of the contact patterns or contact across the surfaces from tooth root to tooth top were obtained as a function of machine settings. The influence of each cutting parameter was isolated and is discussed for kinematic optimization

MODELLING OF GEAR CHANGING BEHAVIOUR

This paper deals with the modelling of the gear changing behaviour. After presentation of the main synchronizer tasks, the state of the art is described. Reconsideration of the gear changing process allows better definition of synchronizer working phases. Based on this, a numerical simulation software of the synchronizer behaviour has been realized. Phenomena of angular velocity synchonization and second bump in gear changing force are modelled in details. Various mechanical behaviour influencing phenomena are taken into consideration with large number of input parameters. The software is validated with literature data. Then, it is used to investigate the effect of main parameters considered with gear changing process for a 5 speed manual car gearbox. Effects of gear changing force, synchronized inertia and initial angular velocity difference variations are shown. Visualization of parameter effects such as angle error of synchronizer cone and relative position of gear splines and sleeve splines help for better understanding of gearbox behaviour during gear changing

Eléments de maintenance préventive de machines tournantes dans le cas de défauts combinés d'engrenages et de roulements

Le monde de l'industrie et le monde des transports disposent de machines et d'installations de plus en plus performantes. Les exigences d'exploitations donnent à la maintenance une rôle prépondérant. Elle doit permettre de n'intervenir qu'en présence d'éléments défectueux, de fournir un diagnostic fiable et facilement interprétable. Ce travail a permis de fournir des éléments supplémentaires concernant le diagnostic de transmission de puissance à engrenages dans le cas de défauts combinés d'engrenages et de roulements. A partir d'un modèle expérimental de réducteur simple étage, des défauts d'engrenages et de roulements ont été simulés. Les grandeurs physiques mesurées pour différentes conditions de fonctionnement étaient l'erreur de transmission, ainsi que les accélérations recueillies sur trois paliers différents. L'analyse de ces données a permis de conclure que l'analyse spectrale et cesptrale du signal enveloppe des accélérations était un outil de diagnostic des roulements quelles que soient les conditions de fonctionnement et l'état des autres organes mécaniques. D'autre part, il a été montré que seules les accélérations mesurées à proximité du roulement à surveiller étaient distinctement porteuses de la signature de l'avarie. Concernant les engrenages, il est connu que l'analyse des accélérations au palier est efficace pour leur diagnostic. Cependant, il a été montré que ce résultat n'est valable qu'en cas de roulements sains. Dans le cas contraire, le signal d'erreur de transmission s'avère être un outil supplémentaire, représentatif de l'état des engrenages. Ces différents résultats ont abouti à l'établissement d'une démarche de diagnostic pour la surveillance de transmissions de puissance à engrenages. D'autre part, nous avons abordé le problème de l'automatisation de diagnostic par l'utilisation de réseaux de neurones. Ceux-ci sont efficaces pour l'automatisation d'une démarche préétablie, mais aussi pour l'optimisation des paramètres d'identification d'avaries recherchées.Machinery used in industrial and transport domains have to be more and more efficient. So, the maintenance of such systems is very important. Interventions must only happen in presence of real damage, and the diagnostic must be reliable and easy to read. This work gave a new elements about the diagnostic of gears power transmissions in case of combined faults of gears and bearings. Gear and bearing faults have been artificially created on an experimental set-up. Transmission error and the bearings accelerations were measured for different operating conditions. Result analysis showed that accelerations envelope signal is an efficient tool for bearings diagnostic, for all operating conditions even in the presence of other defective mechanical components. Moreover, we showed that only accelerations measured in the vicinity of the defective bearing produce a significant pattern of fault presence. According to literature, accelerations analysis produce reliable information about gears health. Yet, we showed that such results are only valid in the case of bearings without any fault. In the presence of simultaneous bearing and gear faults, the transmission error appears as an useful tool giving supplementary information about the gear faults. The obtained results and the established indicators lead to an efficient diagnostic process applied on gear power transmission systems. Moreover, automation of maintenance preventive has been assessed, using neural networks, the used approaches seem to be efficient for the automation procedures, and provides a powerful tool for the optimisation of established indicators.VILLEURBANNE-DOC'INSA LYON (692662301) / SudocSudocFranceF

Thermal Behavior of Power Gearing Transmission, Numerical Prediction, and Influence of Design Parameters

International audienceThermal behavior prediction of Power Gearing Transmissions during preliminary design becomes necessary in order to optimize all the parts of mechanical systems (lubrication, cooling device dimensioning, static and dynamic stress resistance, etc.). It also reduces prototype tests. The thermal network method is used to model each technological element as a thermal finite element and a nonlinear system of equations is obtained. Geometric discretization is adapted to the scale of phenomenological observation and result requirements. As assumptions have to be made for the modeling of convection heat transfer and oil flow, experimental verifications are made. The influence of gear parameters, the effect of time varying running conditions, and oil flow defaults are then studied and discussed

Simulation et analyse du bruit d'engrènement

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Advantages and perspectives of gear Transmission Error measurement with optical encoders

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A systematic approach of the effect design parameter on spectral and wavelet gear noise analysis

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