A Life Estimation Method of the Plastic Helical Gear and Spur Gear Pairs(Machine Elements and Manufacturing)

The plastic gear is widely used in AV equipment, OA equipment and car components, etc. It is often used for power transmission especially in OA equipment and car components. Strength of the tooth for the breakage becomes a problem when it is used for the power transmission. The temperature of the plastic gear in the operation largely affects on the strength because a plastic has a mechanical property of temperature dependency. However, the effect of the temperature of the plastic gear in the operation is not sufficiently considered in the commonly used gear design method. In this study, various combination of gear pair were set for the molded plastic helical gear pair. Then, the relation between load condition, temperature of meshing tooth and life of gears was examined by the experiment. From the result of the experiment, we examined the following methods; (1) the life prediction method based on the temperature of meshing teeth; (2) life prediction method based on arbitrary atmospheric temperature and load condition. Then, whether the life prediction method was appropriate was evaluated. And, whether the method could apply in the spur gear pear was also examined.