Conical hydrodynamic bearing device and a recording disk drive equipped with it, and a method of manufacturing a conical hydrodynamic bearing device

A conical hydrodynamic bearing device, comprising:

• a shaft bush having a conical inclined dynamic pressure surface around an outer circumference thereof being relatively-rotatably inserted in a bearing sleeve having a conical inclined dynamic pressure surface around an inner circumference thereof,
• said inclined dynamic pressure surface of at least either said shaft bush or said bearing sleeve being formed continuously from the cutting start edge along the predetermined cutting direction through a cutting process with a proper cutting tool;
• lubricant fluid being filled in said conical inclined bearing space which is created in the gap between said inclined dynamic pressure surfaces of said bearing sleeve and shaft bush;
• a proper dynamic pressure generating means being formed on at least one of said inclined dynamic pressure surfaces of said shaft bush and bearing sleeve;
• said lubricant fluid being pressurized by said dynamic pressure generating means to generate dynamic pressure, by which said shaft bush and said bearing sleeve are relatively elevated in the radial direction and in the thrust direction so that their rotations are supported in a non-contact manner;
• wherein a gap reference surface which is used for creating a reference gap between said shaft bush and said bearing sleeve in the axial direction is cut integrally with said inclined dynamic pressure surface on at least either said shaft bush or said bearing sleeve or a member integrated with either said member, and a cutting reference surface which is used for detecting the position of said cutting tool in the radial direction and in the axial direction being formed continuously and integrally with said inclined dynamic pressure surface on at least either said shaft bush or said bearing sleeve.

A method of manufacturing a conical hydrodynamic bearing device comprising the steps of:

• relatively rotatably inserting a shaft bush having a conical inclined dynamic pressure surface around the outer circumference thereof in a bearing sleeve having a conical inclined dynamic pressure surface around the inner circumference thereof;
• and
• forming at least either said inclined dynamic pressure surface of said shaft bush or that of said bearing sleeve continuously from the cutting start edge along a predetermined cutting direction through a cutting process by a proper cutting tool;
• filling lubricant fluid in a conical inclined bearing space which is created in a gap between said inclined dynamic pressure surfaces of said shaft sleeve and shaft bush;
• forming a proper dynamic pressure generating means on at least one of said inclined dynamic pressure surfaces of said shaft bush and bearing sleeve;
• pressurizing said lubricant fluid by said dynamic pressure generating means to generate dynamic pressure, with which said shaft bush and said bearing sleeve are relatively elevated in the radial and thrust directions so that their rotations are supported in a non-contact manner;
• cutting a gap reference surface, which is used for creating a reference gap in the axial direction between said shaft bush and said bearing sleeve integrally and continuously with said inclined dynamic pressure surface in either said shaft bush or said bearing sleeve or a member integrated with either said member;
• when said inclined dynamic pressure surface is cut by said cutting tool, forming a cutting reference surface which is used for detecting the position of said cutting tool in the radial and axial directions continuously and integrally with said inclined dynamic pressure surface;
• measuring the position of said cutting tool by the cutting of said reference surface by said tool;
• and
• continuously cutting said inclined dynamic pressure surface based on said measured position of said cutting tool.