Sintered bearing and manufacturing process therefor
AssigneeNtn Corporation
InventorsYoshinori Ito, Tomonori Yamashita
Life of this patent
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Abstract
A sintered bearing (1) contains as main components iron, copper, a metal having a lower melting point than copper, and a solid lubricant. The sintered bearing (1) includes a surface layer (S1) and a base part (S2). The surface layer (S1) is formed mainly of flat copper powder arranged so as to be thinned in a thickness direction. In the base part (S2), an iron structure (33) and a copper structure (31c) brought into contact with the iron structure are formed of partially diffusion-alloyed powder in which copper powder is partially diffused in iron powder. Thus, a sintered bearing which achieves a balance between wear resistance of a bearing surface and strength of the bearing, and realizes low cost can be provided.
Claims11
A manufacturing method of a sintered bearing, which contains as main components iron, copper, an element having a lower melting point than copper, and a solid lubricant, and comprises a base part containing an iron structure and a copper structure, and a surface layer containing a copper structure,
- the element having the lower melting point than copper being any of tin, zinc and phosphorus,
- the sintered bearing having a radial crushing strength of 300 MPa or more, and
- the surface layer covering a surface of the base part, wherein,
- the manufacturing method comprises the steps of:
- mixing partially diffusion-alloyed powder, flat copper powder having an aspect ratio of 13.3 to 160, powder of the element having the lower melting point than copper, and solid lubricant powder to form a mixed powder;
- forming a green compact with the mixed powder;
- and
- sintering the green compact at a temperature lower than a melting point of copper,
- wherein the partially diffusion-alloyed powder is obtained by partially diffusing a plurality of grains of copper powder on a surface of iron powder, a grain diameter of the copper powder of the partially diffusion-alloyed powder being smaller than that of the iron powder of the partially diffusion-alloyed powder,
- wherein an average grain diameter of the partially diffusion-alloyed powder is 106 μm or less, and
- wherein the copper structure of the surface layer is formed by sintering of the flat copper powder, and the iron structure and the copper structure of the base part are formed by sintering of the partially diffusion-alloyed powder.
Dependencies are inferred from the claim text.