Dynamic disc pack balance correction

• US 6,418,612 B1
• Filed: 06/09/2000
• Issued: 07/16/2002
• Est. Priority Date: 10/16/1997
• Status: Expired due to Fees

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Chuang, Thomas Hong, Horning, Steve Gregory, Jenkins, James Randal
• Primary Examiner(s): Hall, Carl E.
• Application Number:
  US09/591,616
• Time in Patent Office: 767 Days
• Field of Search: 296/030.3, 295/96, 297/29, 734/60, 734/61, 734/62, 734/68, 73/66
• US Class Current: 29/603.03
• CPC Class Codes: G11B 17/038 Centering or locking of a plurality of discs in a single cartridge
• CPC Class Codes: G11B 19/04 Arrangements for preventing, inhibiting, or warning against double recording on the same blank or against other recording or reproducing malfunctions
• CPC Class Codes: G11B 25/043 using rotating discs
• CPC Class Codes: G11B 33/08 Insulation or absorption of undesired vibrations or sounds
• CPC Class Codes: Y10T 29/49009 Dynamoelectric machine
• CPC Class Codes: Y10T 29/49025 Making disc drive
• CPC Class Codes: Y10T 29/49764 with testing or indicating
• CPC Class Codes: Y10T 29/53039 with control means energized in response to activator stimulated by condition sensor
• CPC Class Codes: Y10T 29/53165 Magnetic memory device
• CPC Class Codes: Y10T 29/53365 Multiple station assembly apparatus
• CPC Class Codes: Y10T 29/5337 including assembly pallet
• CPC Class Codes: Y10T 29/534 Multiple station assembly or disassembly apparatus
• CPC Class Codes: Y10T 29/53435 including assembly pallet

Abstract

A method for automatically correcting the dynamic imbalance of a disc pack of a disc drive, the disc pack conveyed to a first selected position in a balance correction assembly station where a rotary positioner lifts and rotates the disc pack to a reference position for the attachment of weighted shims to the disc pack. A shim selector assembly delivers a selected shim, and an end effector transfers the selected shim to a shim attachment assembly. The shim attachment assembly rotates and spreads open the shim so that the disc pack can be receivingly engaged thereby, and the shim attachment assembly releases the selected shim to lockingly engage the disc pack. A flipping assembly reverses the disc pack for placement of another selected shim to the other end of the disc pack, as required.

Claims

1. A method of assembling a disc drive from a plurality of component parts comprising a disc pack having a disc drive motor with a disc attached thereto, the method comprising the following steps:

(a) conveying the disc pack into a balance correction station;

(b) determining a selected shim weight and a position of the selected shim weight on the disc drive motor to dynamically balance the disc pack;

(c) selecting the selected shim weight from a plurality of different spreadable shim weights;

(d) spreading the selected shim on a shim spreader assembly;

(e) positioning the shim spreader assembly to position the selected shim at a reference position;

(f) orienting the disc pack at the reference position;

(g) positioning the selected shim weight onto the disc drive motor; and

(h) releasing the selected shim so that the shim grippingly engages the disc drive motor.

2. The method of claim 1 further comprising the following steps:

(i) inverting the disc pack by a flipping assembly;

(j) determining a second selected shim weight and a position of the second shim weight on the disc drive motor to dynamically balance the disc pack;

(k) selecting the second shim weight from a plurality of different spreadable shim weights;

(l) spreading the second shim weight on the shim spreader assembly;

(m) positioning the shim spreader assembly to position the second shim weight at the reference position;

(n) orienting the disc pack at the reference position;

(o) positioning the second shim weight onto the disc drive motor; and

(p) releasing the second shim weight that the second shiin weight grippingly engages the disc drive motor.

3. The method of claim 1, wherein the conveying step (a) further comprises a step of picking up the disc pack with a transfer assembly consisting of a top collet assembly that maintains both the rotational position of a timing mark so that a shim is installed relative to that timing mark maintaining a planar compliancy that can accommodate positional variations of the shim.

4. The method of claim 2, wherein at least one of the selecting steps (c) and (k) further comprises a step of selecting from a number of stacks of shims distinguished by a characteristic such as the width of a shim gap, automatically engaging the desired shim, and delivering it to a shim attachment assembly wherein the selection depends on the shim characteristic and the determination of at least one of the steps (b) and (j).

5. The method of claim 2, wherein at least one of the spreading steps (d) and (l) further comprises a step of using pins and guiding slots such that the center of a shim is maintained in the desired plane.

6. The method of claim 2, wherein at least one of the positioning steps (e) and (m) further comprises a step of providing positive feedback of the distance to the reference position.

7. The method of claim 2, wherein at least one of the orientating steps (f) and (n) further comprises a step of raising up the disc pack with a transfer assembly which comprises a two-axis positioner that supports a collete assembly moving in a horizontal direction along a horizontal guide and in a vertical direction along a vertical guide such that the collete remains positionally fixed relative to the positioner.

8. The method of claim 2, wherein at least one of the positioning steps (g) and (o) further comprises a step of verifying that the shim is attached substantially squarely on the spindle motor.