Moreover, tools have been built capable of machining gear teeth in the hard, tough materials which advances in metallurgy have made available. Since those early times, correct gear-tooth profiles and proportions have been developed. Loads and speeds, however, were moderate and vegetable or animal oils sufficed as lubricants. With this advance, lubrication assumed an important role in reducing wear and prolonging the life of the gear. The first metal gears were probably cast of either bronze or iron. Gears with teeth instead of pegs were made by mortising or keying individual hard wood pieces of the desired profile into the rim of a wheel. The first big forward step in gear design came when peg teeth were abandoned, and teeth shaped much like those in modern gears were developed. Lubrication was of little concern then, for when a tooth wore or broke, its replacement was a simple matter. They were crude affairs and the loads that were transmitted were necessarily lightspeeds were low. The teeth of these early gears were pegs fashioned out of wood and inserted in the rims of wooden wheels. In the earliest machines that man built to do his work, gears formed an essential part. This paper introduces a method and steps based on Pro / E parametric drive to forming involute modified spur gear, with the same way to automatically generate model of base circle larger and smaller than root circle, simplify the procedures. Finally, the simulation results are compared with results from literature and the model. Especially for the case of root relieved teeth that is shown to be more effective in reduction of vibration in the presence of tooth localized defect.
It is indicated that although profile modifications and profile errors are micro-geometrical, which considerable effects on vibrations of gear pair also. Interactions between tooth modifications and profile error are studied and the role of profile modification in dynamic response when a localized defect is incurred by a tooth is shown. In this paper a six degree-of-freedom nonlinear dynamic model including different gear errors and defects is developed for investigation of effects of tooth localized defect and profile modifications on overall gear dynamics. Dynamic modeling of gear vibration used for increasing information about vibration generating mechanisms in gearboxes and dynamic behavior of gearbox in the presence of some kind of gear defects. Vibration induced by gears includes important data about gearbox condition. also it helpful to analyze the results with actual model. Modification and atomization parameters for spur gears is technique to generate the series of same kind of model having different dimensions using standard models like PRO-E, CATIA etc.
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