Abstract
Linear ball guideways are widely employed in machine tool drive systems. Friction fluctuation of linear ball guideways cause the fluctuation of feed rate which results in the contour error in synchronous motions using several feed drives. A model-based systematic methodology to design the raceway profile is demanded to reduce the friction fluctuation of rolling guideways. In this study, a model to estimate the rolling resistance fluctuation of a ball sandwiched by two raceways was proposed. The rolling resistance fluctuation was estimated from the contact angle between the ball and raceways. The contact angle was obtained from the surface profile of the raceway. The estimation accuracy of the proposed model was verified by comparing measured and estimated rolling resistances. The raceway that was finished by face milling with a R-bite was used in the experiment to have rolling resistance fluctuation due to a periodic surface profile. The experimental results showed that the rolling resistance fluctuation could be estimated by the proposed model with 30% amplitude error at maximum. The variation of the rolling resistance was influenced by the phase difference between the upper and lower raceway profiles. The rolling resistance variation could be decreased to 1/3 when the phase difference was 1/2 period of the periodic profile component.
