Magnetic hard disk storage device

Abstract

In order to reduce the cost of producing an in-hub a magnetic hard disk storage device having a motor, which consists of a hub and the motor which is located in this hub and which contains magnets, magnetic yokes, coils, and shieldings, the hub ( 2 ) made of magnetizable steel is coated at least on the outer surface ( 20 ) with a noncorrosive coating which is reduced by means of final machining in the completed state of the motor.

What is claimed is:  
     
       1. In-hub motor comprising: 
       a fixed shaft extending axially of the motor;  
       a stator mounted on the fixed shaft;  
       a pair of ball bearings mounted on the fixed shaft axially spaced apart from each other on either axial end of the stator;  
       a rotor mounted over and at least foundationally supported by both said axially spaced apart ball bearings to rotate around the stator and be separated therefrom by a cylindrical air gap, the rotor including  
       a yoke body of magnetic material having a cylindrical inner surface and a cylindrical outer surface and formed to axially span both said spaced apart ball bearings in support of the rotor and  
       ring shaped permanent magnets mounted on the inner surface of the yoke body opposite the stator and defining an extent of the air gap; and  
       a coating of machinable noncorrosive material applied to the outer surface of the yoke body, said coating being of a predetermined thickness to provide a surface capable of being machined to reduce radial eccentricity in a finished motor.  
     
     
       2. Motor according to  claim 1 , wherein said predetermined thickness of the coating of machinable noncorrosive material is within a range of from 15 μ to approximately 200 μ. 
     
     
       3. In-hub motor comprising: 
       a fixed shaft extending axially of the motor;  
       a stator mounted on the fixed shaft;  
       a pair of ball bearings mounted on the fixed shaft axially spaced apart from each other on either axial end of the stator;  
       a rotor mounted over and at least foundationally supported by both said axially spaced apart ball bearings to rotate around the stator and be separated therefrom by a cylindrical air gap, the rotor including  
       a yoke body of magnetic material having a cylindrical inner surface and a cylindrical outer surface and formed to axially span both said spaced apart ball bearings in support of the rotor and  
       ring shaped permanent magnets mounted on the inner surface of the yoke body opposite the stator and defining an extent of the air gap; and  
       a casing of noncorrosive material of predetermined thickness having two axially opposing ends, one of which is for securing the casing to the yoke body of the rotor, the casing being made to conform to the outer surface of the yoke body and being nested over the outer surface of the yoke body providing a machinable surface for reducing radial eccentricity in a finished motor.  
     
     
       4. Motor according to  claim 3 , wherein the casing of noncorrosive material further has at its mounting end a thickened rim with a mounting borehole therethrough, the rim turning radially toward the inside of the motor. 
     
     
       5. Motor according to  claim 3 , wherein the casing of noncorrosive material further has at its end opposite its mounting end a flange with a planar surface which turns radially outwardly of the motor and terminates in a radially outer end. 
     
     
       6. Motor according to  claim 5 , wherein the yoke body also includes a radially outwardly extending flange terminating in a radially outer end, the yoke body flange extending in parallel to the casing flange at the casing end opposite its mounting end and further including a surrounding groove with an axial recess provided between the radial outer ends of the two flanges. 
     
     
       7. Motor according to  claim 4  wherein the yoke body includes a radially inwardly extending flange in parallel to the thickened rim, the flange mounting directly on an adjacent bearing and supporting the thickened rim. 
     
     
       8. Motor according to  claim 3 , wherein said predetermined thickness of said casing is within a range of from 15 μ to 2 mm. 
     
     
       9. Motor according to  claim 3 , wherein the noncorrosive material is aluminum. 
     
     
       10. A disk storage device, comprising: 
       
         a clean room having an internal mounting surface;  
       
       
         at least one hard magnetic storage disk provided in said clean room for rotation about an axis, said at least one disk having a central opening;  
       
       
         at least one read/write head mounted in said clean room for movement in operative relation to said at least one disk;  
       
         a motor mounted on the internal mounting surface of said clean room for rotating said at least one disk about said axis, said motor including a stator and a bearing and shaft assembly, said assembly including a shaft extending axially of the motor and bearings surrounding said shaft, said motor further including a rotor which is rotatable via said bearings about said axis, said rotor including a cylindrical yoke body of magnetic material and a plurality of ring - shaped permanent magnets connected to said yoke body such that a cylindrical air gap is defined between adjacent surfaces of said permanent magnets and said stator, said motor further including a coating of a machinable noncorrosive material applied to a cylindrical outer surface of said rotor which extends through the central opening of and thereby supports said at least one disk, said coating being of a predetermined thickness to provide a surface capable of being machined to generally reduce radial eccentricity in a finished motor.   
     
     
       11. The disk storage device of  claim 10  wherein said motor comprises an in- hub motor.   
     
     
       12. The disk storage device of  claim 10  further comprising at least one seal for generally sealing the motor compartment from clean room. 
     
     
       13. The disk storage device of  claim 12  wherein said at least one seal comprises at least one magnetic fluid seal. 
     
     
       14. The disk storage device of  claim 10  wherein said coating is applied to the outer surface of said rotor by means of a chosen from the group consisting of: dipping, sputtering, galvanization, and evaporation. 
     
     
       15. The disk storage device of  claim 10  wherein the predetermined thickness of said coating is within a range of from about  15 μ to about  2  mm. 
     
     
       16. The disk storage device of  claim 10  wherein said coating is aluminum. 
     
     
       17. The disk storage device of  claim 10  wherein said magnetic material comprises steel. 
     
     
       18. A disk storage device, comprising: 
       
         a clean room having an internal mounting surface;  
       
       
         at last one hard magnetic storage disk provided in said clean room for rotation about an axis, said at least one disk having a central opening;  
       
       
         at least one read/write head mounted in said clean room for movement in operative relation to said at least one disk;  
       
         a motor mounted on the internal mounting surface of said clean room for rotating said at least one disk about said axis, said motor including a stator and a bearing and shaft assembly, said assembly including a shaft extending axially of the motor and bearings surrounding said shaft, said motor further including a rotor which is rotatable via said bearings about said axis, said rotor including a cylindrical yoke body of magnetic material and a plurality of ring - shaped permanent magnets connected to said yoke body such that a cylindrical air gap is defined between adjacent surfaces of said permanent magnets and said stator, said motor further including a machinable noncorrosive casing of a predetermined thickness applied to a cylindrical outer surface of said rotor which extends through the central opening of and thereby mounts said at least one disk, said casing having two axially opposing ends, one of which is for securing said casing to the cylindrical outer surface of said rotor, said casing being made to conform to and be nested over the cylindrical outer surface of said rotor to provide a machinable surface for generally reducing radial eccentricity in a finished motor.   
     
     
       19. The disk storage device of  claim 18  wherein said motor comprises an in- hub motor.   
     
     
       20. The disk storage device of  claim 18  further comprising at least one seal for generally sealing the motor compartment from clean room. 
     
     
       21. The disk storage device of  claim 20  wherein said at least one seal comprises at least one magnetic fluid seal. 
     
     
       22. The disk storage device of  claim 18  wherein said coating is applied to the outer surface of said rotor by means of a chosen from the group consisting of: dipping, sputtering, and galvanization. 
     
     
       23. The disk storage device of  claim 18  wherein the predetermined thickness of said coating is within a range of from about  15 μ to about  2  mm. 
     
     
       24. The disk storage device of  claim 18  wherein said casing is aluminum. 
     
     
       25. The disk storage device of  claim 18  wherein said magnetic material comprises steel. 
     
     
       26. The disk storage device of  claim 18  wherein said casing of non- corrosive material has a mounting end secured to an axial end of said cylindrical yoke body, said mounting end including a thickened rim with a mounting borehole therethrough, said rim turning radially toward the inside of said motor.   
     
     
       27. The disk storage device of  claim 18  wherein said casing of noncorrosive material further has at its end opposite its mounting end a flange with a planar surface which turns radially outwardly of the motor and terminates in a radially outward end. 
     
     
       28. The disk storage device of  claim 27  wherein said yoke body includes a radially outwardly extending flange terminating in a radially outer end, said yoke body flange extending in parallel to said coating flange at the coating end opposite its mounting end, said yoke body further including a surrounding groove with an axial recess provided between the radial outer ends of the two flanges. 
     
     
       29. The disk storage device of  claim 26  where said yoke body includes a radially inwardly extending flange in parallel to the thickened rim, the flange mounting directly on an adjacent bearing and supporting the thickened rim. 
     
     
       30. The disk storage device of  claim 18  wherein said casing is applied to the cylindrical outer surface of said rotor by means of a technique chosen from the group consisting of: shrink coating, bonding, and magnetic molding.