Wear of Glass-Fiber-Reinforced Polyamide Worm Gear According to the Direction of the Glass Fiber

摘要

Wear of glass-fiber-reinforced polyamide composites for C-EPS (Column-type Electric Power Steering) worm gear is studied. Main focus of this work is given to moisture absorption of the composites and its effect on wear characteristics. Worm gears in 3 different types are manufactured by modifying the injection design using glass fibers and polyamide (PA12). Mechanical properties of the gears, such as hardness and strength, are evaluated first in terms of the orientation of glass fibers in the composite and then tribological properties are examined. The friction and wear of the worm gear was measured by a specially designed friction tester for worm gears, which measures amount of wear and backlash. Results indicate that the worm gear manufactured by the upper injection design shows the lowest backlash increase compared to the other two cases. Amount of backlash is also decreased by using upper injection design in a wide range operation condition. Particularly noteworthy is the finding that the contact angle of glass fiber has a remarkable effect on the wear characteristics.