Production method for sintered fluid dynamic pressure bearing

Abstract

A sintered fluid dynamic pressure bearing completely seals or decreases the sizes of gaps formed in pores by shrinkage when a resin impregnated therein shrinks. The fluid dynamic pressure bearings can be reliably and easily produced using fewer processes while superior quality is maintained. A production method for a fluid dynamic pressure bearing includes a resin sealing process including a resin impregnating step in which a monomer of an anaerobic resin composed primarily of acrylate or methacrylate is impregnated in pores of a porous sintered compact, an excess resin washing off step in which excess resin adhering to the surface of the porous sintered compact is washed off, and a resin curing step in which the monomer of the anaerobic resin impregnated in the pores is cured by heating the porous sintered compact to at least the curing temperature of the resin after washing off the excess resin; the resin sealing process is repeatedly carried out, and a monomer of an anaerobic resin containing an organic peroxide at 0.1 to 1.0 mass % is used in at least the resin impregnating step of the last resin sealing process.

1 . A production method for a fluid dynamic pressure bearing, comprising a resin sealing process comprising: 
 a resin impregnating step in which a monomer of an anaerobic resin composed primarily of one of acrylate and methacrylate is impregnated into pores of a porous sintered compact;    an excess resin washing off step in which excess resin adhering to a surface of the porous sintered compact is washed off; and    a resin curing step in which the monomer of the anaerobic resin impregnated in the pores is cured by heating the porous sintered compact to at least a resin curing temperature after washing off the excess resin,    wherein the resin sealing process is carried out at least twice, and the monomer of the anaerobic resin containing an organic peroxide at 0.1 to 1.0 mass % is used in at least the resin impregnating step of the last resin sealing process.    
   
   
       2 . The production method for a fluid dynamic pressure bearing, according to  claim 1 , wherein the monomer of the anaerobic resin containing an azo compound at 0.1 to 0.5 mass % is used in at least the resin impregnating step of the first resin sealing process.  
   
   
       3 . The production method for a fluid dynamic pressure bearing, according to  claim 1 , wherein the monomer of the anaerobic resin containing an organic peroxide at 0.1 to 1.0 mass % is used in the resin impregnating step of the first resin sealing process, and the resin impregnating step is carried out under a pressure of 10 2  to 10 3  Pa.  
   
   
       4 . The production method for a fluid dynamic pressure bearing, according to  claim 1 , wherein the organic peroxide is at least one hydroperoxide selected from t-butyl hydroperoxide, cumene hydroperoxide, di-isopropyl peroxide, p-methane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, and benzoyl peroxide.  
   
   
       5 . The production method for a fluid dynamic pressure bearing, according to  claim 1 , wherein the anaerobic resin composed primarily of acrylate or methacrylate contains a curing accelerator comprising an organometallic compound at not more than 1.0 mass %.  
   
   
       6 . The production method for a fluid dynamic pressure bearing, according to  claim 1 , wherein the porous sintered compact is made of a copper-iron-based material in which 3.0 to 30 mass % of copper foil powder is contained in a raw material powder and Cu content is at least 20 mass %.  
   
   
       7 . The production method for a fluid dynamic pressure bearing, according to  claim 1 , wherein the porous sintered compact is subjected to a size adjusting repressing step which adjusts a size of the porous sintered compact, and a fluid dynamic pressure groove forming repressing step in which a groove for generating fluid dynamic pressure is provided on at least one of a bore surface and an edge surface of the porous sintered compact by a deformation processing, before the resin sealing process.