Rotating device, manufacturing method thereof and bearing component

Abstract

A manufacturing method of a bearing component for a dynamic pressure bearing is provided. The method includes forming a plurality of individual recesses in a groove dispose area in an end face of the bearing component along respective turns of a spiral line having a distance from a center of the bearing component gradually increasing turn by turn from an inner circumference of the groove dispose area to an outer circumference thereof. Each of the plurality of individual recesses is disposed so as to partially overlap at least one adjoining individual recess in a radial direction to form a thrust dynamic pressure generating groove.

What is claimed is: 
     
         1 . A manufacturing method of a bearing component for a dynamic pressure bearing, the manufacturing method comprising:
 a groove machining step for forming a plurality of individual recesses in a groove dispose area in an end face of the bearing component along respective turns of a spiral line having a distance from a center of the bearing component gradually increasing turn by turn from an inner circumference of the groove dispose area to an outer circumference thereof,   wherein each of the plurality of individual recesses is disposed so as to partially overlap at least one adjoining individual recess in a radial direction to form a thrust dynamic pressure generating groove.   
     
     
         2 . The bearing component manufacturing method according to  claim 1 , wherein the groove machining step comprises:
 reciprocating a machining tool in an axial direction of the bearing component so as to alternately repeat a contacting condition and a non-contacting condition with the groove dispose area while the bearing component is rotated; and   simultaneously, moving the machining tool from one of an inner circumference side of the groove dispose area and an outer circumference side of the groove dispose area to the other of the inner circumference side of the groove dispose area and the outer circumference side of the groove dispose area.   
     
     
         3 . The bearing component manufacturing method according to  claim 2 , wherein in the groove machining step, a cycle of the rotation of the bearing component is set to be an integral multiple of a cycle of the reciprocation of the machining tool. 
     
     
         4 . The bearing component manufacturing method according to  claim 2 , wherein in the groove machining step, the reciprocation of the machining tool is performed using a piezoelectric element. 
     
     
         5 . The bearing component manufacturing method according to  claim 2 , wherein in the groove machining step, a center position of a tip of the machining tool in the reciprocation in the axial direction is located outside the bearing component. 
     
     
         6 . The bearing component manufacturing method according to  claim 2 , further comprising, prior to the groove machining step, a pre machining step for decreasing a squareness of the groove dispose area relative to a rotation center. 
     
     
         7 . The bearing component manufacturing method according to  claim 6 , wherein a clamping condition of the bearing component to a machining apparatus is maintained between a beginning of the pre machining step and an end of the groove machining step. 
     
     
         8 . The bearing component manufacturing method according to  claim 6 , wherein a machining allowance of the bearing component in the axial direction in the pre machining step is larger than a depth dimension of the individual recess in the axial direction in the groove machining step. 
     
     
         9 . The bearing component manufacturing method according to  claim 1 , further comprising, after the groove machining step, a post machining step for decreasing an unevenness of a portion of the groove dispose area where no individual recess is formed. 
     
     
         10 . The bearing component manufacturing method according to  claim 9 , wherein a clamping condition of the bearing component to a machining apparatus is maintained between a beginning of the groove machining step and an end of the post machining step. 
     
     
         11 . The bearing component manufacturing method according to  claim 9 , wherein a machining allowance of the bearing component in the axial direction in the post machining step is smaller than a depth dimension of the individual recess in the axial direction in the groove machining step. 
     
     
         12 . A manufacturing method of a disk drive device, wherein the disk drive device comprises a stationary body, a rotating body including a recording disk, a bearing mechanism that supports the rotating body in a freely rotatable manner relative to the stationary body, and a rotating/driving unit that rotates the rotating body, and wherein the manufacturing method comprises:
 a groove machining step for forming a plurality of individual recesses in a groove dispose area in an end face of a cylindrical member forming the bearing mechanism along respective turns of a spiral line having a distance from a rotation axis of the rotating body gradually increasing turn by turn from an inner circumference of the groove dispose area to an outer circumference thereof, the end face of the cylindrical member being perpendicular to the rotation axis,   wherein each of the plurality of individual recesses is disposed so as to partially overlap at least one adjoining individual recess in a radial direction to form a thrust dynamic pressure generating groove.   
     
     
         13 . The disk drive device manufacturing method according to  claim 12 , wherein the groove machining step comprises:
 rotating the cylindrical member around the rotation axis of the rotating body;   reciprocating a machining tool in an axial direction of the cylindrical member so as to alternately repeat a contacting condition and a non-contacting condition with the groove dispose area while the cylindrical member is rotated; and   simultaneously, moving the machining tool from one of an inner circumference side of the groove dispose area and an outer circumference side of the groove dispose area to the other of the inner circumference side of the groove dispose area and the outer circumference side of the groove dispose area.   
     
     
         14 . The disk drive device manufacturing method according to  claim 13 , wherein in the groove machining step, a cycle of the rotation of the cylindrical member is set to be an integral multiple of a cycle of the reciprocation of the machining tool. 
     
     
         15 . The disk drive device manufacturing method according to  claim 13 , wherein in the groove machining step, the reciprocation of the machining tool is performed using a piezoelectric element. 
     
     
         16 . The disk drive device manufacturing method according to  claim 13 , wherein in the groove machining step, a center position of a tip of the machining tool in the reciprocation is located outside the bearing component in the axial direction. 
     
     
         17 . The disk drive device manufacturing method according to  claim 12 , further comprising, prior to the groove machining step, a pre machining step for decreasing a squareness of the groove dispose area relative to the rotation axis,
 wherein a clamping condition of the bearing component to a machining apparatus is maintained between a beginning of the pre machining step and an end of the groove machining step.   
     
     
         18 . The disk drive device manufacturing method according to  claim 17 , wherein a machining allowance of the cylindrical member in the axial direction in the pre machining step is larger than a depth dimension of the individual recess in the axial direction in the groove machining step. 
     
     
         19 . The disk drive device manufacturing method according to  claim 12 , further comprising, after the groove machining step, a post machining step for decreasing an unevenness of a portion of the groove dispose area where no individual recess is formed,
 wherein a clamping condition of the bearing component to a machining apparatus is maintained between a beginning of the groove machining step and an end of the post machining step.   
     
     
         20 . The disk drive device manufacturing method according to  claim 19 , wherein a machining allowance of the cylindrical member in the axial direction in the post machining step is smaller than a depth dimension of the individual recess in the axial direction in the groove machining step.