Static stiffness analysis of an electronically preloaded rack and pinion feed drive system

Rack and pinion feed drives are commonly selected for large machine tools with long travel distances due to their consistent stiffness, which remains unaffected by axis stroke. To mitigate the inherent backlash between the pinion and the rack, a double pinion setup with electronic preload, managed via CNC is typically used. This commissioned preload value not only influences the acceleration capacity, but also the stiffness behaviour of the feed drive system as demonstrated in this study. A coupled master-slave controlled rack and double pinion model is developed and validated through static stiffness measurements on a large-scale machine tool at varying levels of electronic preload.