Sintered bearing and manufacturing method for same

Abstract

Provided is a sintered bearing ( 1 ), including 3 to 12% by mass of aluminum, 0.05 to 0.5% by mass of phosphorus, and the balance including copper as a main component, and inevitable impurities, the sintered bearing ( 1 ) having a structure in which an aluminum-copper alloy is sintered with a sintering aid added to raw material powder, a pore (db, do) in a surface layer portion of the sintered bearing ( 1 ) being formed smaller than an internal pore (di).

1 . A sintered bearing, comprising 3 to 12% by mass of aluminum, 0.05 to 0.5% by mass of phosphorus, and the balance comprising copper as a main component, and inevitable impurities,
 the sintered bearing having a structure in which an aluminum-copper alloy is sintered with a sintering aid added to raw material powder,   a pore in a surface layer portion of the sintered bearing being formed smaller than an internal pore.   
     
     
         2 . The sintered bearing according to  claim 1 , wherein the sintered bearing has added thereto, as the sintering aid, 1 to 4% by mass of silicon and 0.5 to 2% by mass of tin with respect to the raw material powder. 
     
     
         3 . The sintered bearing according to  claim 1 , wherein the sintered bearing has added thereto, as the sintering aid, a total of 0.05 to 0.2% by mass of aluminum fluoride and calcium fluoride with respect to a total of 100% by mass of the raw material powder comprising aluminum, phosphorus, and the balance comprising copper as a main component, and the inevitable impurities. 
     
     
         4 . The sintered bearing according to  claim 3 , wherein the sintered bearing has added thereto 2 to 4% by mass of zinc. 
     
     
         5 . The sintered bearing according to  claim 3 , wherein the sintered bearing has added thereto 0.5 to 3% by mass of silicon. 
     
     
         6 . The sintered bearing according to  claim 1 , wherein the copper in the raw material powder comprises electrolytic copper powder as a main component. 
     
     
         7 . The sintered bearing according to  claim 1 , wherein the sintered bearing has added thereto 1 to 5% by mass of graphite with respect to a total of 100% by mass of the raw material powder and the inevitable impurities. 
     
     
         8 . The sintered bearing according to  claim 1 , wherein: the sintered bearing has a compressed layer in a surface layer; a density ratio (α1) of the compressed layer is higher than a density ratio (α2) of an inside; the density ratio (α1) is 80%≦α1≦95; and a ratio (T/D 1 ) of an average value (T) of depths of the compressed layer and an inner diameter dimension (D 1 ) of a bearing surface is 1/100≦T/D 1 ≦ 1/15. 
     
     
         9 . The sintered bearing according to  claim 1 , wherein, in an outer surface of the sintered bearing, a pore on a bearing surface is formed larger than a pore on the remaining outer surface. 
     
     
         10 . The sintered bearing according to  claim 1 , wherein the sintered bearing comprises an oil-impregnated bearing. 
     
     
         11 . The sintered bearing according to  claim 1 , wherein the sintered bearing is used for a fuel pump and comprises aluminum in an amount of from 8 to 9% by mass. 
     
     
         12 . A manufacturing method for a sintered bearing comprising 3 to 12% by mass of aluminum, 0.05 to 0.5% by mass of phosphorus, and the balance comprising copper as a main component, and inevitable impurities,
 the manufacturing method comprising at least:   a green compact forming step of forming a green compact in which a sintering aid is added to raw material powder;   a sintering step of obtaining, from the green compact, a sintered compact having a structure in which an aluminum-copper alloy is sintered; and   a sizing step of subjecting the sintered compact to dimension shaping.   
     
     
         13 . The manufacturing method for a sintered bearing according to  claim 12 , wherein the sintered bearing has added thereto, as the sintering aid, a total of 0.05 to 0.2% by mass of aluminum fluoride and calcium fluoride with respect to a total of 100% by mass of the raw material powder comprising aluminum, phosphorus, and the balance comprising copper as a main component, and the inevitable impurities. 
     
     
         14 . The manufacturing method for a sintered bearing according to  claim 12 , wherein the copper in the raw material powder comprises electrolytic copper powder as a main component. 
     
     
         15 . The manufacturing method for a sintered bearing according to  claim 12 , wherein the sintered bearing has added thereto 1 to 5% by mass of graphite with respect to a total of 100% by mass of the raw material powder and the inevitable impurities. 
     
     
         16 . The manufacturing method for a sintered bearing according to  claim 12 , wherein: a form in the sizing step comprises a die, a pair of punches, and a core; and the sizing step comprises compressing the sintered compact from both sides in an axial direction and a radially outer side with the punches and the die to shape a radially inner side of the sintered compact with the core. 
     
     
         17 . The manufacturing method for a sintered bearing according to  claim 12 , wherein the sizing step comprises setting a size of a pore on a surface of the sintered compact by adjusting a dimension difference between an inner diameter dimension of the die and an outer diameter dimension of the sintered compact and a dimension difference between an outer diameter dimension of the core and an inner diameter dimension of the sintered compact. 
     
     
         18 . The manufacturing method for a sintered bearing according to  claim 12 , wherein the sintering step comprises using a mesh-belt type continuous furnace. 
     
     
         19 . The manufacturing method for a sintered bearing according to  claim 12 , wherein a sintering temperature of the sintering step is from 850 to 950° C. 
     
     
         20 . The manufacturing method for a sintered bearing according to  claim 12 , wherein: a sintering atmosphere of the sintering step comprises a reducing atmosphere; and a sintering time of the sintering step is from 10 to 60 minutes.