| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 93 === A helical gear is one of the important transmission elements in a machine system and often used for parallel axes gearing. The manufacture methods can be categorized into the cutting method and the non-cutting method. A powder metallurgy helical gear belongs to the non-cutting method and has great advantages of material-saving, labor-saving, fitness for mass production, cost down and good mechanical properties. It has been widely used in the industry.
In the powder metallurgy helical gear manufacturing, the gear surface deviations are due to the influences of powders, green density, sintering time, sintering temperature and the design of a forming die. To improve the gear manufacture precision without changing the mechanical properties of the gears and other process parameters, correcting the shape of the forming die to compensate the metallurgy helical gear surface deviations would be feasible.
This study refers to the conditions of practical powder metallurgy manufacture process, and proceeds to experiments and gear precision measurements as well as investigation on the effects of two parameters, powders and pitch circle radius, on gear precision. The relationship between gear parameters and gear surface deviations was derived from the mathematical model for the involute helical gears and the analysis of gear surface deviations. In accordance with the measurement results of experiments, an ideal correction on the parameters of a forming die could be derived from the computer simulations of gear surface deviations.
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