A newly developed zero-gravity vertical motion mechanism for precision machining

Gravity load deteriorates positioning performance on a vertical motion stage. A counterweight or a fluidic cylinder is conventionally used for gravity compensation; however, these solutions may induce new problems. This paper presents a novel zero-gravity vertical motion mechanism for precision machining. The proposed mechanism employs a linear motor and the magnet yoke has rolling guideway, thus the yoke is also used as counter mass. Because inertia of the moving parts is doubled for disturbance, the mechanism can effectively minimize the influence of machining force. The performance evaluation results confirm that the mechanism provides superior driving characteristics to vertical motion stages.