| 摘要 |
PROBLEM TO BE SOLVED: To restrain fluctuation in the friction coefficient to the low level and prolong the service life by providing a sliding surface without a cavity over the whole circumferential region at one end of the inner circumferential surface of bearing hole, and making the other part contiguous thereto a porous part for supplying lubricant. SOLUTION: On an inner circumferential surface 5 of bearing hole 4, a first sliding surface 6 is formed without a pore over the whole circumferential region from the axial center to one opening end side, and being contiguous thereto a second slide surface 7 is formed with a high pore ratio toward the other opening end. As for the manufacturing method, after law material powder is filled in a change chamber R of metal mold D, pressure formation is applied thereto by an upper punch 9 and punching out a lower punch 10 upward, and an upper step part forming a recess 11a of core rod 11 upon the punching out operation pressurize the law material powder in the chamber R so that pores are fill(4 up thereby. Accordingly the friction coefficient with a rotation shaft 2 is kept law and the balance of oil Pressure is kept constant through supply of lubricant to the second slide surface 7, thereby keeping low the fluctuation of friction coefficient, leading to extension of service life. |
