Low distortion interference fits for spindle motor assembly

• US 5,793,129 A
• Filed: 05/30/1997
• Issued: 08/11/1998
• Est. Priority Date: 03/02/1995
• Status: Expired due to Term

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology plc (Seagate Technology Holdings Plc)
• Inventors: Murthy, Samnathan, Leuthold, Hans, Parsoneault, Norbert Steven, Jennings, David John
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): Jones, Judson H.
• Application Number:
  US08/866,810
• Time in Patent Office: 438 Days
• Field of Search: 310/42, 310/67 R, 360/78.13, 360/104, 360/106, 29/525, 29/596, 29/598
• US Class Current: 310/216.048
• CPC Class Codes: F16C 17/045 with grooves in the bearing surface to generate hydrodynamic pressure, e.g. spiral groove thrust bearings
• CPC Class Codes: F16C 2370/12 Hard disk drives or the like
• CPC Class Codes: F16C 33/107 Grooves for generating pressure
• CPC Class Codes: G11B 19/2009 Turntables, hubs and motors for disk drives; Mounting of motors in the drive means for clamping of disk to turntable G11B17/022 and subgroups
• CPC Class Codes: G11B 19/2027 Turntables or rotors incorporating balancing means; Means for detecting imbalance
• CPC Class Codes: H02K 5/1677 radially supporting the rotor around a fixed spindle; radially supporting the rotor directly
• CPC Class Codes: Y10T 29/49009 Dynamoelectric machine
• CPC Class Codes: Y10T 29/49945 by driven force fit

Abstract

For a precision spindle motor, an invention for reducing distortion resulting from interference fits of a thrust plate to spindle motor shaft and of a counter plate to a journal. A method of assembly according to the invention includes the step of balancing an interference pressure about a centerline of at least one of the thrust plate and the counter plate of the spindle motor. A precision spindle motor according to the invention comprises a journal having a bore defined therein, a shaft located in the bore, a thrust plate mounted to a top portion of the shaft by means of an interference fit, and a counter plate mounted to the journal adjacent to the thrust plate by means of an interference fit, wherein an interference pressure is balanced about a centerline of at least one of the thrust plate and the counter plate.

Claims

1. A method of assembly of a precision spindle motor, the motor including a journal and a counter plate, the method comprising the step of interference fitting an outer side surface of the counter plate to an inner interference surface of the journal, the outer side surface of the counter plate defines a non-cylindrical shape for balancing an interference pressure about the centerline of the counter plate.

2. A method of assembly of a precision spindle motor, the motor including a journal and a counter plate, the method comprising the step of interference fitting an outer side surface of the counter plate to an inner interference surface of the journal, the inner interference surface of the journal defines a non-cylindrical shape for balancing an interference pressure about the centerline of the counter plate.

3. A method of assembly of a precision spindle motor, the motor including a journal and a counter plate, the method comprising the step of interference fitting an outer side surface of the counter plate to an inner interference surface of the journal, the inner interference surface of the journal defines a taper for balancing an interference pressure about the centerline of the counter plate.

4. A precision spindle motor comprising:

a journal having a bore defined therein, the journal including a tube-like protrusion defining an inner interference surface;

a shaft located in and extending from the bore of the journal, a top portion of the shaft extending from the bore, the top portion of the shaft including an outer interference surface;

a thrust plate having a hole defined therein by an inner surface of the thrust plate, the thrust plate being mounted to the top portion of the shaft by means of an interference fit between the outer interference surface of the shaft and the inner surface of the thrust plate;

a counter plate including an outer side surface, the counter plate being mounted to the journal adjacent to the thrust plate by means of an interference fit between the inner interference surface of the journal and the outer side surface of the counter plate, wherein an interference pressure is balanced about a centerline of the counter plate.

5. A precision spindle motor according to claim 4 wherein at least one of the outer side surface of the counter plate and the inner interference surface of the journal defines a non-cylindrical shape for balancing an interference pressure about the centerline of the counter plate.

6. A precision spindle motor according to claim 5 wherein the inner interference surface defines a taper for balancing an interference pressure about a centerline of the counter plate.