Method of Manufacturing Porous Bearing Component, and Method of Manufacturing Fluid Dynamic-Pressure Bearing Furnished with the Porous Bearing Component

Abstract

Manufacturing method for impregnating with lubricant a porous bearing material retained in a bearing retaining cavity in a bearing retainer. Under a reduced-pressure space within a vacuum chamber, a bearing structural unit in which a porous bearing material is retained in a bearing retaining cavity in a bearing retainer is, with an opening in the bearing structural unit directed down, immersed in or contacted on lubricant to cover over the bearing-structural-unit opening; by then restoring chamber pressure, the porous bearing material is impregnated with the lubricant. The manufacturing method controls to a minimum adhesion of lubricant to the bearing-retainer exterior, to eliminate as far as possible the trouble of lubricant cleanup, and at the same time makes the impregnation of the porous bearing material with lubricant more sound and facilitates the impregnation job despite its being under a reduced-pressure atmosphere.

1 . A method of manufacturing a lubricant-impregnated porous bearing component, in which a bearing retainer having a bearing retaining cavity at least one end of which is open, and a tubular porous bearing material retained in the bearing retaining cavity in the bearing retainer constitute a bearing structural unit in which the bearing-retaining-cavity interior except for the one end portion of the bearing retainer has airtightness against the outside, the method impregnating the porous bearing material with a lubricant, and comprising: 
 a step of, within a vacuum chamber in which the lubricant is contained, disposing the bearing structural unit separated from the lubricant;    a step of reducing the pressure within the vacuum chamber in which the bearing structural unit is disposed;    a step, under the reduced-pressure state within the vacuum chamber, and with the one end of the bearing retaining cavity directed down, of immersing in, or contacting on, the lubricant the one end portion of the bearing retainer to occlude the one end of the bearing retaining cavity;    a step of maintaining the one end of the bearing retaining cavity occluded by the lubricant and infiltrating the lubricant inside the bearing retainer; and    a step of, with the one end of the bearing retaining cavity occluded by the lubricant, restoring the pressure within the vacuum chamber.    
   
   
       2 . A lubricant-impregnated porous bearing component manufacturing method according to  claim 1 , wherein in immersing the one end portion of the bearing structural unit in, or contacting the one end portion on, the lubricant arranged within the vacuum chamber, to put the one end of the bearing retaining cavity in an occluded state, the porous bearing material retained within the bearing retaining cavity is immersed in or contacted on the lubricant.  
   
   
       3 . A lubricant-impregnated porous bearing component manufacturing method according to  claim 2 , wherein after immersing the one end portion of the bearing structural unit in, or contacting the one end portion on, the lubricant arranged within the vacuum chamber, and immersing in or contacting on the lubricant the porous bearing material retained within the bearing retaining cavity, to put the one end of the bearing retainer in an occluded state, following the elapse of a predetermined period of time, pressure is restored while the state in which the one end portion is occluded by the lubricant is maintained.  
   
   
       4 . A lubricant-impregnated porous bearing component manufacturing method according to  claim 1 , further comprising an operation, in maintaining the one end of the bearing retaining cavity occluded by the lubricant and infiltrating the lubricant inside the bearing retainer, of elevating the liquid surface of the lubricant within the vacuum chamber, or lowering the bearing retainer.  
   
   
       5 . A lubricant-impregnated porous bearing component manufacturing method according to  claim 1 , wherein: 
 the bearing structural unit is of a structure in which the bearing-retaining-cavity interior except for the one end portion of the bearing retainer does not have airtightness against the outside; and    the manufacturing method further comprises the step of, before the one end portion of the bearing structural unit disposed within the vacuum chamber is immersed in or contacted the lubricant, making the bearing retainer except for the one end of the bearing retaining cavity airtight against the outside.    
   
   
       6 . A lubricant-impregnated porous bearing component manufacturing method according to  claim 1 , wherein subsequent to the step of restoring the pressure within the vacuum chamber with the one end of the bearing retaining cavity being occluded by the lubricant, the occlusion by the lubricant is broken after the elapse of a predetermined period of time.  
   
   
       7 . A lubricant-impregnated porous bearing component manufacturing method according to  claim 1 , wherein the porous bearing material constitutes a bearing sleeve part, opening along the one end portion, of the bearing structural unit.  
   
   
       8 . A method of manufacturing a lubricant-impregnated porous bearing component, in which a bearing retainer having a bearing retaining cavity at least one end of which is open, and a tubular porous bearing material retained in the bearing retaining cavity in the bearing retainer constitute a bearing structural unit in which the bearing-retaining-cavity interior except for the one end portion of the bearing retainer has airtightness against the outside, the method impregnating the porous bearing material with a lubricant, and comprising: 
 placing the bearing structural unit within a reduced-pressure space;    with the one end of the bearing retaining cavity directed down, immersing in, or contacting on, the lubricant the one end portion of the bearing retainer to put the one end of the bearing retaining cavity in an occluded state; and    thereafter, while maintaining the one end of the bearing retaining cavity occluded by the lubricant, restoring the pressure to impregnate the porous bearing material with the lubricant.    
   
   
       9 . A method of manufacturing a fluid dynamic-pressure bearing furnished with a shaft-end structural unit having a centrally protruding shaft, a shaft-end ringlike planar surface extending radially outward from the outer circumferential surface of the base of the shaft, and a cylindrical surrounding wall surface standing out, in the same direction as the shaft, from the shaft-end ringlike planar surface along its outer periphery, and furnished with a bearing structural unit open along one side, having a journaling bore into which the shaft is inserted, a closed-off endface axially opposing the leading-end surface of the shaft, an open-side endface axially opposing the shaft-end ringlike planar surface, and a bearing-side outer circumferential surface confronting the cylindrical surrounding wall surface across a diametrical interspace; the bearing structural unit retaining, in a bearing retaining cavity of a unilaterally open-ended bearing retainer, a sleeve-shaped porous bearing material forming the journaling bore, and the porous bearing material being impregnated with lubricant; the fluid dynamic-pressure bearing being constituted such that a series of bearing gaps filled with lubricant is formed between the bearing structural unit, and the shaft and the shaft-end ringlike planar surface, and such that the lubricant interposes continuously between the cylindrical surrounding wall surface and the bearing-side outer circumferential surface; the fluid-dynamic-pressure bearing manufacturing method comprising: 
 placing the bearing structural unit within a reduced-pressure space;    with the one end of the bearing structural unit directed down, immersing the one end portion in, or contacting the one end portion on, lubricant arranged within the reduced-pressure space to put the one end portion in state in which it is occluded by the lubricant; and    thereafter, while maintaining the one end portion occluded by the lubricant, restoring the pressure to impregnate the porous bearing material with the lubricant.