Ultraprecision Positioning by Preload Change of Lead Screws : Characteristics of Fine Feed

概要

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Ultraprecision positioning is examined for a fine feed system utilizing the elastic deformation of lead screws accompanying the change in the preload in a double nut. The nonlinear deformation due to Hertzian contact of the ball screw can be ignored within a feed of 1μm under an adequate initial preload. No effect of table load on nanometer-order displacement is observed in the range from 10 to 50kg. The table displacement obtained under an increase in the preload coincides well with the result under a decrease in the preload. Feed control with preload change based on a one-to-one correspondence of preload change and displacement is effective for avoiding the hysteresis phenomenon of the piezoelectric actuator adopted as a deformable spacing part in a double nut. In addition, the preload can be used as a measure to detect the table displacement in place of a position sensor which sometimes shows unreliability owing to unstable performance in the nanometer region. The minimum step feed deduced from preload change is 1nm for a sliding screw and 5nm for a ball screw.
一般社団法人日本機械学会の論文
2001-09-15