Sintered bearing and method of manufacturing same
A sintered bearing includes a sintered metal formed by using a metal powder mixture containing copper powder and iron powder. The metal powder mixture contains 80 wt % or more of particles having an average particle diameter of less than 45 μm. The copper powder contains electrolytic copper powder. The electrolytic copper powder contains 40 number % or more of particles having a circularity of 0.64 or more.
1. A sintered bearing, comprising a sintered metal formed by using a metal powder mixture containing copper powder and iron powder,
the metal powder mixture containing 80 wt % or more of particles having an average particle diameter of less than 45 μm,
the copper powder containing electrolytic copper powder containing 40 number % or more of particles having a circularity of 0.64 or more.
2. The sintered bearing according to claim 1 , wherein the copper powder contains 85 wt % or more of particles having an average particle diameter of less than 45 μm.
3. The sintered bearing according to claim 1 , wherein the copper powder contains less than 10 wt % of particles having an average particle diameter of less than 10 μm.
4. The sintered bearing according to claim 1 , wherein the electrolytic copper powder has an apparent density of from 1.4 g/cm 3 to 1.7 g/cm 3 .
5. The sintered bearing according to claim 1 , wherein the metal powder mixture contains 50 wt % to 60 wt % of the electrolytic copper powder.
6. The sintered bearing according to claim 1 , wherein the iron powder contains 80 wt % or more of particles having an average particle diameter of less than 45 μm.
7. The sintered bearing according to claim 1 , wherein the iron powder comprises reduced iron powder.
8. The sintered bearing according to claim 1 , comprising a sintered metal containing 38 wt % to 42 wt % of iron and 1 wt % to 3 wt % of tin, with the balance being copper and unavoidable impurities.
9. A fluid dynamic bearing device, comprising:
the sintered bearing of claim 1 ;
a shaft member inserted into an inner periphery of the sintered bearing; and
a lubricating oil filled into a radial bearing gap formed between an inner peripheral surface of the sintered bearing and an outer peripheral surface of the shaft member.
10. A motor, comprising:
the fluid dynamic bearing device of claim 9 ;
a stator coil; and
a rotor magnet.
11. A method of manufacturing a sintered bearing, comprising:
subjecting a metal powder mixture containing copper powder and iron powder to compression molding to form a compact; and
sintering the compact at a predetermined sintering temperature,
the metal powder mixture containing 80 wt % or more of particles having an average particle diameter of less than 45 μm,
the copper powder containing electrolytic copper powder containing 40 number % or more of particles having a circularity of 0.64 or more.
12. The method of manufacturing the sintered bearing according to claim 11 , wherein the copper powder contains 85 wt % or more of particles having an average particle diameter of less than 45 μm.
13. The method of manufacturing the sintered bearing according to claim 11 , wherein the copper powder contains less than 10 wt % of particles having an average particle diameter of less than 10 μm.
14. The method of manufacturing the sintered bearing according to claim 11 , wherein the electrolytic copper powder has an apparent density of from 1.4 g/cm 3 to 1.7 g/cm 3 .
15. The method of manufacturing the sintered bearing according to claim 11 , wherein the metal powder mixture contains 50 wt % to 60 wt % of the electrolytic copper powder.
16. The method of manufacturing the sintered bearing according to claim 11 , wherein the iron powder contains 80 wt % or more of particles having an average particle diameter of less than 45 μm.
17. The method of manufacturing the sintered bearing according to claim 11 , wherein the iron powder comprises reduced iron powder.
18. The method of manufacturing the sintered bearing according to claim 11 , comprising a sintered metal containing 38 wt % to 42 wt % of iron and 1 wt % to 3 wt % of tin, with the balance being copper and unavoidable impurities.