Method for manufacturing sintered bearing, sintered bearing, and vibration motor equipped with same

Patent metadata

Field	Value
Publication number	US-10536048-B2
Application number	US-201414777889-A
Country	US
Kind code	B2
Filing date	Mar 19, 2014
Priority date	Mar 25, 2013
Publication date	Jan 14, 2020
Grant date	Jan 14, 2020

Abstract

The present invention relates to a method for manufacturing a sintered bearing having a bearing surface that forms a bearing gap with a shaft to be supported, in its inner periphery. This manufacturing method includes: a compacting step P 2 of compacting a base powder containing a diffusion alloyed powder 11 prepared by partially diffusing a copper powder in an iron powder as a main material, a low-melting-point metal powder 14 , and a solid lubricant to obtain a green compact, and a sintering step P 3 of sintering the green compact 4 ′ to obtain a sintered compact 4″.

First claim

The invention claimed is:

1. A vibration motor comprising:
a shaft;
a motor part for rotationally driving the shaft;
a sintered bearing having a bearing surface on an inner periphery thereof, for rotatably supporting the shaft;
a weight disposed on the shaft; and
a housing having an inner periphery on which the sintering bearing is fixed by press-fitting, the vibration motor generating vibration by making the shaft eccentrically rotate with respect to the bearing center by the weight,
wherein the sintered bearing is formed of a sintered compact containing iron as a main ingredient, copper as a second major ingredient, and an element selected from tin, zinc, and phosphorus, and has a radial crushing strength of greater than or equal to 300 MPa,
wherein the sintered bearing includes an iron structure and copper structures which are formed by sintering a diffusion alloyed powder formed by diffusing a plurality of copper powders on a surface of an iron powder, the copper structures being partly diffused in the iron structure, and the copper structures being mutually bonded by the element,
wherein the copper structures have a smaller size than that of the iron structure, and an entirety of the sintered bearing is free from a segregation of the copper structures, and
wherein the diffusion alloyed powder has a mean grain diameter of less than or equal to 106 μm, and does not contain 25% by mass or more of grains having the mean grain diameter of less than or equal to 45 μm.

2. The vibration motor according to claim 1 , wherein the sintered bearing further comprises free graphite.

3. The vibration motor according to claim 2 , wherein the iron powder of the diffusion alloyed powder is a reduced iron powder.

4. The vibration motor according to claim 2 , wherein
the sintered compact is composed of 10 to 30% by mass of copper, 0.5 to 3.0% by mass of tin, 0.3 to 1.5% by mass of carbon, and iron and inevitable impurities as a balance.

5. The vibration motor according to claim 1 , wherein the iron structure of the sintered compact is based on a ferrite phase.

6. The vibration motor according to claim 1 , wherein the iron structure of the sintered compact is composed of a ferrite phase, and a pearlite phase existing in a grain boundary of the ferrite phase.

7. The vibration motor according to claim 1 , wherein porosity of a superficial part of the sintered compact is 5 to 20%.

8. The vibration motor according to claim 1 , wherein the sintered compact is impregnated with a lubricating oil having a kinematic viscosity at 40° C. ranging from 10 to 50 mm 2 /s.

9. The vibration motor according to claim 1 , wherein a sintered bearing is disposed on both sides in an axial direction of the motor part.

10. The vibration motor according to claim 9 , wherein of the sintered bearings disposed on both sides in the axial direction of the motor part, the sintered bearing of one side is disposed between the weight and the motor part, and an axial dimension of the sintered bearing of the one side is larger than an axial dimension of the sintered bearing of the other side.

Assignees

• Ito Yoshinori
• Sugai Yousuke
• Ntn Toyo Bearing Co Ltd

Inventors

• Ito Yoshinori
• Sugai Yousuke

Classifications

• B22F1/05

  Metallic powder characterised by the size or surface area of the particles · CPC title

• B22F1/17

  Metallic particles coated with metal · CPC title

• C22C33/0207

  Using a mixture of pre-alloyed powders or a master alloy · CPC title

• B22F5/10

  of articles with cavities or holes, not otherwise provided for in the preceding subgroups · CPC title

• H02K5/167

  using sliding-contact or spherical cap bearings · CPC title