Abstract
Using an electric resistance method, the authors measured the states of oil film formation during one stroke of the improved type ball screw which incorporates resin retaining pieces between balls. As lubricating oil, two kinds of mineral oil with much different viscosity were used. The screw shaft is rotated in the range of 120rpm〜950rpm. The results were compared with the experimental results in the grease lubricated condition. In the case of the high viscosity mineral oil, the oil film between balls and raceways was formed sufficiently even at a lower shaft speed of N=120rpm. On the other hand, the oil film formation with the low viscosity mineral oil or with the grease was influenced by the rotating speed of screw shaft. Using a magnetized ball and hall elements, the ball motion in ball screw was also measured, and the relationship between the ball motion and the oil film formation was discussed.
