| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a dynamic pressure bearing having less wear and longer service life while suppressing friction against a shaft, which likely occurs when starting or stopping a motor, and resultantly quickly starting the rotation of the motor, and to provide its manufacturing method. <P>SOLUTION: Electric discharging or chemical etching is applied to a punch face 52b of an upper punch 52 to form a protruded portion 52a as part of a spiral groove 12 and to form a number of fine irregularities on the punch face 52b into a coarse face. A sintered bearing material 1A is compressed in a re-compression process by the upper punch 52 and the protruded portion 52a is engraved on an upper end face 11 thereof to form the spiral groove 12, and the irregularities on the punch face 52b is transferred thereto to form the number of fine irregularities on the upper end face 11 into a coarse face. A fine recessed portion in the upper end face 11 is functioned as an oil sump to suppress friction against the shaft 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
