FLUID DYNAMIC PRESSURE BEARING AND SPINDLE MOTOR

摘要

PROBLEM TO BE SOLVED: To achieve the proper distribution and smooth flow of a lubricant in a fluid dynamic pressure bearing having a flanged shaft constituted of a ring member formed with thrust dynamic pressure grooves on the upper face and the lower face and radial dynamic pressure grooves on the outer periphery respectively and a columnar member pressed into the ring member. SOLUTION: This fluid dynamic pressure bearing comprises the flanged shaft 1 constituted of the ring member 3 formed with the thrust dynamic pressure grooves G2 on the upper face and the lower face and the radial dynamic pressure grooves G1 on the outer periphery respectively and the columnar member 2 pressed into the ring member 3; a sleeve 4 rotatably coupled with the flanged shaft 1; and an annular cover member 5 functioning as a thrust pressing member. Multiple pairs of slender lubricant reservoir holes Q21, Q22 extending obliquely inward in the radial direction from the upper and lower edge portions of the outer periphery of the ring member 3 are formed at uniform intervals in the peripheral direction. A lubricant reservoir hole Q23 is formed at least at one position in the vertical direction near the rotation center on the bottom face of the shaft 1. An oil repellent process is applied to the depth sections B of the lubricant reservoir holes Q21, Q22 and the depth section D of the lubricant reservoir hole Q23 so that bubbles can be easily retained.