Abstract
The fatigue life of injection molded plastic gear is greatly affected by the plastic material and temperature. Because the stiffness of plastic depends on its material and temperature, and plastics are viscoelastic materials. On the other hand, natural materials are used to focus on the ecological recycling. The rice hull is a residual product of rice, and it contains natural silica about 20wt%. The authors focused on using the Rice-Hull-Silica-Carbon (RHSC) as a reinforcing material in plastic. In this study, Polyacetal (POM) and POM filled with RHSC, were used for the materials of test gears. The fatigue life and noise of test gear were investigated under fixed rotational speed and some torque. Then, the effects of RHSC on the fatigue and noise of plastic gear were studied experimentally. From the discussions, it seems reasonable to conclude:(1) In a RHSC-gear, RHSC-particles exist on a tooth surface, and these grind a tooth surface of partner. The size of grinding trace depends on the size of RHSC-particle. (2) The sliding-sound of tooth is lower when a tooth is worn out. However, since a tooth will be more worn if RHSC-particle is large, the sliding-sound increases.
