Hydrodynamic bearing member and manufacturing method thereof

Abstract

The present invention aims to improve the efficiency of a clamping step for combining a flange with a shaft and to improve productivity. The shaft and the flange are tentatively combined in the tentative clamping step. In the tentative clamping step, a concave part at the end of the shaft is pressurized by a metal mold such as a ball to be enlarged in an outer circumferential direction, thereby pressurizing this concave part against the inner circumference of the flange so as to fix the concave part. The combined body made by tentatively combining the shaft and the flange is strongly combined in a proper clamping step. In order to correct a distortion such as a warpage of the flange that has been solidly combined by the proper clamping step, sandwiching the flange by the upper and lower metals, the flange is pressurized and a flash molding is carried out.

1 - 5 . (canceled) 
   
   
       6 . A manufacturing method of a hydrodynamic bearing member comprising:
 a tentative clamping step of inserting a mounting part of the shaft into a hole of the flange, pressurizing the concave part of the shaft by a metal mold formed in a certain shape to enlarge the mounting part, and tentatively combining the flange with the shaft;   a proper clamping step of pressurizing the opposite faces of the flange by the metal mold while binding the outer circumference of the flange and making the inner circumferential part of the hole of the flange to bite into the step part of the shaft to clamp the flange with the shaft in the flange and the shaft that were tentatively combined in the tentative clamping step; and   a flash molding step of correcting a distortion of the flange by pressurizing the opposite faces of the flange;   wherein the hydrodynamic bearing member comprises a shaft having a step part with a surface that is approximately vertical to a center axis of a column-shaped member formed at one end of the column-shaped member, and a mounting part having a diameter larger than the minimum diameter of the step part and forming a concave part on the end face; and a flange shaped in a disc having a hole into which the mounting part of the shaft is inserted.   
   
   
       7 . The manufacturing method of the hydrodynamic bearing member according to  claim 6 ,
 wherein the front end of the metal mold to pressurize the concave part is shaped in a ball.   
   
   
       8 . The manufacturing method of the hydrodynamic bearing member according to  claim 6 ,
 wherein the metal mold pressurizing the concave part has a plurality of projections, and the projection enlarges the mounting part to the outer circumferential direction.   
   
   
       9 . The manufacturing method of the hydrodynamic bearing member according to  claim 6 ,
 wherein the hydrodynamic bearing member has a groove mold for forming a dynamic pressure generation groove on the abutting face of the flange on at least one pressurized face of each metal mold for pressurizing the opposite faces of the flange in the proper clamping step.   
   
   
       10 . The manufacturing method of the hydrodynamic bearing member according to  claim 6 ,
 wherein the concave part disposed on the end face of the shaft is formed in a cone, a truncated cone or a column.   
   
   
       11 . The manufacturing method of the hydrodynamic bearing member according to  claim 6 ,
 wherein the concave part disposed at the end face of the shaft has an inner diameter that is gradually enlarged toward the end of the shaft.