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This paper introduces a new and effective study on optimum calculation of the partial ratios of coupled planetary gear sets for getting minimum radial size of the gear sets. In the paper, basing on moment equilibrium condition of a mechanic system including two row planetary gear units and their regular resistance condition, an effective model for determining the partial ratios of coupled planetary gear sets was proposed. Especially, by giving this explicit model, the partial ratios can be calculated accurately and simply.

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Abstract:The present work focuses on the performance of nanofluids called CN46-NanoAl 2 O 3 .80 formulated by using dispersions of nano aluminum oxide (Al 2 O 3 ) in the ISO VG46 industrial oil on machining performance during gear hobbing of AISI 4118 steel. In machining gears, hobbing is one of the most important processes, especially to produce various gear shapes for adapting to diverse applications. However, the demand for high quality brings attention to product quality, particularly the roughness of the machined gear surface because of its effect on product appearance, function, and reliability. For additional improvement, applying nanofluids may produce superior product quality, as the rolling action of billions of nanoparticle units in the tool chip interface can significantly decrease the friction led to reduce the cutting forces. In addition, the characteristics of heat transfer of nanoparticles can contribute to reduce tool wear. In this experimental study, the performance of nanolubricant compared with the case of using ordinary cutting-fluid systems in the existing production line is investigated. The experimental results reveal that the tool life of the hob is significantly enhanced of 55.2%, gear surface roughness is smaller (27.3%), and gear accuracy is significantly increased by using the nanofluid. This result, therefore, shows a promising solution to achieve the engineering-economy effectiveness in gear machining.