Study on the use of a non-circular gear train for the generation of Figure-8 patterns

Most popular polishing mechanisms for optical fibre end-face polishing machines are divided into three categories: planetary gear trains, linkages, and programmable logic controllers. To prevent the finished product from being scratched, it is expected that the grinding pattern prevents the lapping surface from repeatedly cutting the optical fibre end face in the same direction during the grinding process. For this reason, a polishing machine, whose grinding pad moves according to a Figure-8 path, is proposed in the present work. A pair of elliptical gears is designed to substitute the anti-parallel four-bar linkage and to drive one point of the coupler link along a Figure-8 pattern. However, owing the kinematic characteristics of elliptical gears, the velocity of the coupler point is highly variable during its motion, which is disadvantageous to the quality of grinding. Thus, in this study, a pair of non-circular gears is proposed as driving mechanism. By providing the driving elliptical gear with a suitable law of motion, it is possible to enable the velocity of the coupler point to be constant. A kinematic simulation has been performed to prove that the use of non-circular gears is effective in improving the motion characteristics of the Figure-8 path of motion, which is generated by elliptical gears.