| 摘要 |
PROBLEM TO BE SOLVED: To retain sufficient rotational accuracy for a long time, by sandwiching a row of balls between two kinds of thrust plates which one of the ball contact surface of a dynamic pressure bearing having a herringbone groove is flat and the other thereof has a rolling groove. SOLUTION: A dynamic pressure bearing is so formed that the groove forming part of a shaft 1 having a herringbone groove 4 generating dynamic pressure is surrounded with a sleeve 2, and lubricating fluid is filled into a clearance between the shaft 1 and the sleeve 2. A row of balls 7, 7' held by retainers 8 is arranged in ball rolling groove 3, 3' formed in both end surfaces of this sleeve 2. Upper and lower flat thrust plates 5, 6 whose contact surfaces are finished into flat surfaces are fixed by sandwiching this row of balls 7, 7'. Therefore, the axial movement of the shaft 1 is restricted in the sleeve 2 by a thrust ball bearing, and the shaft 1 may not be inclined. Thus, at the time of low speed rotation, solid contact between the shaft and the baring becomes line contact, a contact area is widened as that friction is reduced and the life of the bearing can be extended. |
